Fix v1.3.1: File associations and 50/50 pane layout

- Enhanced file association handling for double-clicking .md files
- Added proper file associations in package.json build config
- Fixed preview/source pane layout to be equally distributed 50/50
- Updated CSS for tab-content structure with proper flex layout
- Added theme support for new pane selectors
- Improved command line argument processing for file opening
- Updated version to 1.3.1 with file association feature

CLAUDE.md

@@ -1,189 +1,303 @@
-# Pan Converter
+# PanConverter - Claude Development Guide
 
-## Overview
+## Project Overview
-Pan Converter is a cross-platform desktop application for editing and converting Markdown files using Pandoc. It features a rich markdown editor with live preview, multiple themes, and support for exporting to various formats.
 
-## Features
+**PanConverter** is a cross-platform Markdown editor and converter powered by Pandoc, built with Electron. It provides professional-grade editing capabilities with comprehensive export options.
-- **Markdown Editor**: Full-featured editor with syntax highlighting
-- **Live Preview**: Real-time preview of your markdown content
-- **Multiple Themes**: Light, Dark, Solarized, Monokai, and GitHub themes
-- **Format Conversion**: Export to HTML, PDF, DOCX, LaTeX, RTF, ODT, and EPUB using Pandoc
-- **Cross-Platform**: Runs on Windows, macOS, and Linux
-- **Auto-Save**: Automatic saving every 30 seconds
 
-## Requirements
+**Current Version**: v1.2.1  
-- **Pandoc**: Must be installed on the system for export functionality
+**Author**: Amit Haridas (amit.wh@gmail.com)  
-  - Ubuntu/Debian: `sudo apt-get install pandoc`
+**License**: MIT  
-  - macOS: `brew install pandoc`
+**Repository**: https://github.com/amitwh/pan-converter
-  - Windows: Download from https://pandoc.org/installing.html
 
-## Development Setup
+## Architecture & Technology Stack
+
+### Core Technologies
+- **Electron** - Cross-platform desktop application framework
+- **Pandoc** - Universal document converter (required dependency)
+- **marked** - Markdown parsing and rendering
+- **highlight.js** - Syntax highlighting
+- **XLSX** - Spreadsheet export functionality
+- **DOMPurify** - HTML sanitization
+
+### Application Structure
+```
+src/
+├── main.js        # Electron main process, menu system, IPC handlers
+├── renderer.js    # UI logic, editor functionality, event handling
+├── index.html     # Application layout and components
+└── styles.css     # Comprehensive styling with multi-theme support
+
+assets/
+└── icon.png       # Application icon
+
+package.json       # Dependencies and build configuration
+```
+
+## Development Commands
 
 ### Prerequisites
-- Node.js (v14 or higher)
-- npm or yarn
-- Pandoc (for export features)
-
-### Installation
 ```bash
-# Clone the repository
+# Install Node.js dependencies
-git clone <repository-url>
-cd pan-converter
-
-# Install dependencies
 npm install
 
-# Generate icons
+# Install Pandoc (required for export functionality)
+# Ubuntu/Debian:
+sudo apt-get install pandoc
+
+# macOS:
+brew install pandoc
+
+# Windows: Download from https://pandoc.org/installing.html
+```
+
+### Running the Application
+```bash
+# Start development server
+npm start
+
+# Start with debugging
+npm start --enable-logging
+```
+
+### Building & Packaging
+
+```bash
+# Generate application icons
 npm run generate-icons
 
-# Start the application
+# Build for current platform
-npm start
-```
-
-## Building
-
-### Build for Current Platform
-```bash
 npm run build
-```
 
-### Build for Specific Platforms
+# Platform-specific builds
-```bash
+npm run build:win      # Windows
-# Windows
+npm run build:mac      # macOS
-npm run build:win
+npm run build:linux    # Linux (AppImage, .deb, .snap)
 
-# macOS
+# Build for all platforms
-npm run build:mac
-
-# Linux (generates .deb, .AppImage, and .snap)
-npm run build:linux
-```
-
-### Build for All Platforms
-```bash
 npm run dist:all
 ```
 
-## Project Structure
+### Git Branch Management
-```
+```bash
-pan-converter/
+# Switch to platform-specific branches
-├── src/
+git checkout linux    # Linux development
-│   ├── main.js         # Main process
+git checkout macos     # macOS development  
-│   ├── renderer.js     # Renderer process
+git checkout windows   # Windows development
-│   ├── index.html      # Main window HTML
+git checkout master    # Main development branch
-│   └── styles.css      # Application styles
+
-├── assets/
+# Update all branches with latest changes
-│   ├── icon.svg        # Source icon
+git checkout master
-│   └── icon.png        # Generated icons
+git push origin master
-├── scripts/
+git checkout linux && git merge master && git push origin linux
-│   └── generate-icons.js # Icon generation script
+git checkout macos && git merge master && git push origin macos
-├── package.json        # Project configuration
+git checkout windows && git merge master && git push origin windows
-└── CLAUDE.md          # This file
 ```
 
-## Architecture
+### Release Management
+```bash
+# Create and push release tag
+git tag v1.2.1 -m "Release message"
+git push origin v1.2.1
+
+# Create GitHub release with packages
+gh release create v1.2.1 --title "Title" --notes "Release notes" \
+  "dist/PanConverter-1.2.1.AppImage" \
+  "dist/pan-converter_1.2.1_amd64.deb" \
+  "dist/pan-converter_1.2.1_amd64.snap"
+```
+
+## Feature Implementation Guide
+
+### v1.2.1 Comprehensive Editor Enhancements
+
+#### ✨ Advanced Editor Features
+
+**Find & Replace System** (`src/renderer.js:200-350`)
+- Dialog-based interface with match highlighting
+- Forward/backward navigation through matches
+- Replace single or replace all functionality
+- Real-time match counting and status display
+- Escape key closes dialog
+
+**Line Numbers** (`src/renderer.js:450-500`, `src/styles.css:517-598`)
+- Toggle-able line numbers with toolbar button
+- Synchronized scrolling with editor content
+- Theme-aware styling for all supported themes
+- Dynamic line number generation based on content
+
+**Undo/Redo System** (`src/renderer.js:100-150`)
+- Stack-based state management for editor history
+- Keyboard shortcuts: `Ctrl/Cmd+Z` (undo), `Ctrl/Cmd+Shift+Z` (redo)
+- Intelligent state saving on text changes
+- Memory-efficient history management
+
+**Smart Auto-Indentation** (`src/renderer.js:350-400`)
+- Automatic list continuation on Enter key
+- Proper indentation handling for nested lists
+- Support for ordered and unordered lists
+- Intelligent whitespace management
+
+**Enhanced Keyboard Shortcuts** (`src/renderer.js:400-450`)
+- `Tab`/`Shift+Tab` for line indentation/outdentation
+- `Enter` for auto-continuing lists
+- `Ctrl/Cmd+F` for find & replace dialog
+- `Escape` for closing dialogs
+
+**Word/Character Count** (`src/renderer.js:500-530`)
+- Live counting displayed in status bar
+- Updates automatically as content changes
+- Word and character statistics
+
+#### 📤 Export & Conversion Features
+
+**PowerPoint Export** (`src/main.js:330-350`)
+- Convert markdown to PPTX presentations
+- Automatic slide-level formatting (`--slide-level=2`)
+- Smart presentation structure handling
+
+**Spreadsheet Export** (`src/main.js:370-457`)
+- Export markdown tables to Excel (XLSX/XLS) and ODS formats
+- Multi-table support with separate worksheets
+- Automatic table detection and parsing
+- Error handling for files without tables
+
+**Document Import** (`src/main.js:280-315`)
+- Import DOCX, ODT, RTF, HTML, PDF, PPTX, ODP files
+- Automatic conversion to markdown format
+- File dialog with appropriate filters
+- Success notifications and error handling
+
+**Table Creation Helper** (`src/renderer.js:600-650`)
+- Built-in table generator with row/column specification
+- Automatic markdown table formatting
+- Proper header separation and alignment
+
+#### 🎨 Interface & Theming
+
+**Multi-Theme Support** (`src/styles.css:214-598`)
+- Light, Dark, Solarized, Monokai, GitHub themes
+- Complete theming for all UI components
+- Theme-aware styling for new features (find dialog, line numbers)
+- Persistent theme selection with local storage
+
+**Enhanced UI Components** (`src/index.html:94-108`)
+- Find & replace dialog with modern styling
+- Toolbar buttons for all new features
+- Status bar with live statistics
+- Responsive layout with proper spacing
+
+## File Structure & Key Components
 
 ### Main Process (`src/main.js`)
-- Manages application lifecycle
+- **Menu System**: Comprehensive menu with file operations, editing, conversion, view options
-- Creates and manages windows
+- **IPC Handlers**: Communication between main and renderer processes
-- Handles file operations
+- **File Operations**: Open, save, import/export functionality
-- Manages menu bar
+- **Theme Management**: Persistent theme storage and application
-- Communicates with renderer via IPC
+- **Spreadsheet Export**: Table extraction and XLSX generation
+- **About Dialog**: Application information and feature list
 
 ### Renderer Process (`src/renderer.js`)
-- Handles UI interactions
+- **Editor Initialization**: CodeMirror-like functionality with custom implementation
-- Manages editor state
+- **Find & Replace Engine**: Search algorithms with regex support
-- Renders markdown preview
+- **Undo/Redo Manager**: History stack management
-- Handles theme switching
+- **Auto-indentation Logic**: Smart list continuation
-- Communicates with main process via IPC
+- **Live Preview**: Real-time markdown rendering with DOMPurify
+- **Event Handling**: Keyboard shortcuts and UI interactions
+- **Statistics Tracking**: Word/character counting
 
-### Key Libraries
+### Styling (`src/styles.css`)
-- **Electron**: Desktop application framework
+- **Base Styles**: Application layout and typography
-- **marked**: Markdown parsing
+- **Component Styles**: Toolbar, editor, preview, dialogs
-- **highlight.js**: Syntax highlighting
+- **Theme Implementations**: Complete styling for all themes
-- **DOMPurify**: HTML sanitization
+- **Responsive Design**: Flexible layouts and proper spacing
-- **electron-store**: Persistent storage
+- **Animation Support**: Smooth transitions and hover effects
-- **electron-builder**: Application packaging
 
-## Features Implementation
+### HTML Structure (`src/index.html`)
+- **Toolbar**: Feature buttons with SVG icons
+- **Find Dialog**: Search and replace interface
+- **Editor Container**: Line numbers and text editor
+- **Preview Pane**: Rendered markdown display
+- **Status Bar**: Statistics and application status
 
-### Markdown Editor
+## Testing & Quality Assurance
-- Uses native textarea with custom styling
-- Supports common markdown shortcuts via toolbar
-- Tab key inserts 4 spaces for code indentation
-- Auto-save every 30 seconds when content changes
 
-### Live Preview
+### Manual Testing Checklist
-- Updates in real-time as you type
+- [ ] All keyboard shortcuts work correctly
-- Sanitized HTML output for security
+- [ ] Find & replace functions properly with edge cases
-- Syntax highlighting for code blocks
+- [ ] Line numbers sync correctly with content
-- GitHub-flavored markdown support
+- [ ] Undo/redo preserves cursor position
+- [ ] Auto-indentation works with various list types
+- [ ] All themes render correctly for new components
+- [ ] Export functions work with various document formats
+- [ ] Table creation and export functionality
+- [ ] Cross-platform compatibility
 
-### Theme System
+### Known Issues & Limitations
-- Themes stored in user preferences
+- AppImage may require `--no-sandbox` flag on some Linux systems
-- Applied via CSS classes on body element
+- Large files (>1MB) may cause performance issues
-- Persists across application restarts
+- Windows/Mac builds require platform-specific environments
-- Five built-in themes
+- Pandoc must be installed separately for export functionality
 
-### Export System
+## Deployment & Distribution
-- Uses Pandoc command-line tool
-- Supports multiple output formats
-- Maintains original file structure
-- Shows error messages if Pandoc not installed
 
-## Platform-Specific Branches
+### Release Packages
+- **Linux AppImage**: Universal Linux package (self-contained)
+- **Debian Package**: `.deb` for Ubuntu/Debian systems
+- **Snap Package**: Universal Linux package via Snap Store
+- **Future**: Windows `.exe` and macOS `.dmg` packages
 
-The repository maintains separate branches for platform-specific customizations:
+### Release Process
-- `master`: Main development branch
+1. Update version in `package.json`, `src/main.js`, and `README.md`
-- `linux`: Linux-specific configurations
+2. Commit changes and push to all platform branches
-- `macos`: macOS-specific configurations  
+3. Build platform-specific packages
-- `windows`: Windows-specific configurations
+4. Create Git tag and GitHub release
+5. Upload packages to GitHub release
+6. Update documentation and announce release
 
-## Debian Package
+## Contributing Guidelines
 
-The application can be built as a `.deb` package for Debian-based systems:
+### Code Style
-```bash
+- Use consistent indentation (2 spaces)
-npm run build:linux
+- Follow JavaScript ES6+ standards
-```
+- Comment complex functionality
+- Maintain separation between main and renderer processes
+- Use descriptive variable and function names
 
-The generated `.deb` file will:
+### Adding New Features
-- Install to `/opt/pan-converter`
+1. Plan feature implementation and UI integration
-- Create desktop entry for application menu
+2. Update relevant files (main.js, renderer.js, styles.css)
-- Set up proper file associations
+3. Test across all supported themes
-- Declare Pandoc as dependency
+4. Update documentation and README
+5. Test on multiple platforms if possible
+6. Submit pull request with detailed description
 
-## Testing
+### Bug Reporting
+- Include steps to reproduce
+- Specify platform and version information
+- Attach relevant screenshots or error logs
+- Check existing issues before creating new ones
 
-### Manual Testing
+## Future Roadmap
-1. File Operations: New, Open, Save, Save As
-2. Editor Features: Bold, Italic, Headings, Links, Code, Lists, Quotes
-3. Preview Toggle: Show/hide preview pane
-4. Theme Switching: Test all five themes
-5. Export Functions: Test each export format
-6. Auto-save: Verify 30-second auto-save works
 
-### Platform Testing
+### Planned Features
-Test on:
+- [ ] Collaborative editing capabilities
-- Windows 10/11
+- [ ] Plugin system for extensions
-- macOS 11+ (Big Sur and later)
+- [ ] Advanced markdown extensions (math, diagrams)
-- Ubuntu 20.04+, Debian 11+
+- [ ] Cloud synchronization options
+- [ ] Mobile companion app
+- [ ] Advanced export templates
+- [ ] Spell check and grammar checking
+- [ ] Version control integration
 
-## Known Issues
+### Technical Improvements
-- ICO and ICNS icons need manual conversion from PNG
+- [ ] Performance optimization for large files
-- Pandoc must be installed separately
+- [ ] Memory usage optimization
-- Large files may cause performance issues
+- [ ] Startup time improvements
+- [ ] Better error handling and user feedback
+- [ ] Automated testing suite
+- [ ] Continuous integration/deployment
 
-## Future Enhancements
+---
-- [ ] Add spell checking
-- [ ] Implement find and replace
-- [ ] Add custom CSS for preview
-- [ ] Support for markdown extensions
-- [ ] Plugin system for custom exporters
-- [ ] Cloud sync capabilities
-- [ ] Collaborative editing
 
-## License
+**Last Updated**: September 1, 2025  
-MIT License
+**Claude Assistant**: Development completed for v1.2.1 comprehensive editor enhancements
-
-## Support
-For issues or feature requests, please open an issue on the GitHub repository.

README.md

@@ -1,29 +1,62 @@
-# Pan Converter
+# PanConverter
 
 A cross-platform Markdown editor and converter powered by Pandoc.
 
-![Pan Converter](assets/icon.png)
+![PanConverter](assets/icon.png)
 
 ## Features
 
-- 📝 **Rich Markdown Editor** - Full-featured editor with syntax highlighting
+### ✨ Advanced Markdown Editor
-- 👁️ **Live Preview** - See your markdown rendered in real-time
+- 🗂️ **Tabbed Interface** - Work with multiple files simultaneously in separate tabs
+- 📝 **Rich Text Editor** - Full-featured editor with syntax highlighting and comprehensive toolbar
+- 🔍 **Find & Replace** - Powerful search and replace with match highlighting and navigation
+- 🔢 **Line Numbers** - Toggle line numbers for easier code editing and navigation
+- ↩️ **Smart Auto-Indentation** - Automatic list continuation and intelligent indentation
+- ⏪ **Undo/Redo** - Full undo/redo support with keyboard shortcuts
+- ⌨️ **Advanced Shortcuts** - Tab indentation, line selection, and smart text formatting
+- 📂 **File Association Support** - Open markdown files directly from file manager
+
+### 🎨 Themes & Interface
+- 👁️ **Live Preview** - See your markdown rendered in real-time with synchronized scrolling
 - 🎨 **Multiple Themes** - Choose from Light, Dark, Solarized, Monokai, or GitHub themes
-- 📤 **Export to Multiple Formats** - Convert to HTML, PDF, DOCX, LaTeX, RTF, ODT, and EPUB
+- 💾 **Auto-Save** - Never lose your work with automatic saving every 30 seconds
-- 💾 **Auto-Save** - Never lose your work with automatic saving
+
-- 🖥️ **Cross-Platform** - Works on Windows, macOS, and Linux
+### 📤 Export & Conversion
+- 📄 **Enhanced PDF Export** - Robust PDF generation with multiple LaTeX engine fallbacks (XeLaTeX, PDFLaTeX, wkhtmltopdf)
+- 📄 **Document Export** - Convert to HTML, DOCX, LaTeX, RTF, ODT, EPUB, PowerPoint (PPTX), and OpenDocument Presentation (ODP)
+- 📊 **Spreadsheet Export** - Export markdown tables to Excel (XLSX/XLS) and OpenDocument Spreadsheet (ODS) formats
+- 📥 **Document Import** - Import DOCX, ODT, RTF, HTML, PDF, and presentation files to markdown
+- 📋 **Table Creation Helper** - Built-in table generator for easy markdown table creation
+
+### 🖥️ Platform Support
+- **Cross-Platform** - Works seamlessly on Windows, macOS, and Linux
 
 ## Installation
 
 ### Prerequisites
 - [Pandoc](https://pandoc.org/installing.html) must be installed for export functionality
+  - **Ubuntu/Debian**: `sudo apt-get install pandoc`
+  - **macOS**: `brew install pandoc`
+  - **Windows**: Download installer from Pandoc website
+
+### PDF Export Requirements
+For optimal PDF export, install a LaTeX engine (recommended):
+- **Ubuntu/Debian**: `sudo apt-get install texlive-xetex texlive-latex-base`
+- **macOS**: `brew install --cask mactex`
+- **Windows**: Install MiKTeX or TeX Live
+- **Alternative**: `sudo apt-get install wkhtmltopdf` (fallback option)
 
 ### Download
-Download the latest release for your platform from the [Releases](https://github.com/yourusername/pan-converter/releases) page.
+Download the latest release for your platform from the [Releases](https://github.com/amitwh/pan-converter/releases) page.
+
+#### Linux
+- **AppImage**: `PanConverter-1.3.0.AppImage` (universal, may require `--no-sandbox` flag)
+- **Debian Package**: `pan-converter_1.3.0_amd64.deb`
+- **Snap Package**: `pan-converter_1.3.0_amd64.snap`
 
 ### Install from Source
 ```bash
-git clone https://github.com/yourusername/pan-converter.git
+git clone https://github.com/amitwh/pan-converter.git
 cd pan-converter
 npm install
 npm start
@@ -31,45 +64,103 @@ npm start
 
 ## Usage
 
+### Basic Workflow
 1. **Write** - Use the editor to write your Markdown content
 2. **Preview** - Toggle the preview pane to see rendered output
 3. **Theme** - Choose your preferred theme from the View menu
-4. **Export** - Export your document to various formats via File > Export
+4. **Export** - Export your document to various formats
+
+### Export Options
+- **Documents**: HTML, PDF, DOCX, LaTeX, RTF, ODT, EPUB
+- **Presentations**: PowerPoint (PPTX), OpenDocument Presentation (ODP)
+- **Spreadsheets**: Excel (XLSX/XLS), OpenDocument Spreadsheet (ODS)
+
+### Import & Conversion
+- **Import Documents**: Convert DOCX, ODT, RTF, HTML, PDF, and presentation files to Markdown
+- **Cross-Format Conversion**: Convert current file between multiple formats
+- **Smart Presentation Handling**: Automatic slide-level formatting for PPTX/ODP exports
+
+### Table Creation
+- Click the table button in the toolbar
+- Specify number of rows and columns
+- Automatically generates properly formatted Markdown tables
 
 ## Keyboard Shortcuts
 
-- `Ctrl/Cmd + N` - New file
+### File Operations
+- `Ctrl/Cmd + N` - New file/tab
+- `Ctrl/Cmd + T` - New tab
+- `Ctrl/Cmd + W` - Close current tab
+- `Ctrl/Cmd + Tab` - Switch to next tab
 - `Ctrl/Cmd + O` - Open file
 - `Ctrl/Cmd + S` - Save file
 - `Ctrl/Cmd + Shift + S` - Save as
+- `Ctrl/Cmd + I` - Import document
+
+### Editor Features
+- `Ctrl/Cmd + F` - Find & Replace
+- `Ctrl/Cmd + Z` - Undo
+- `Ctrl/Cmd + Shift + Z` - Redo
+- `Tab` - Indent lines or insert 4 spaces
+- `Shift + Tab` - Outdent selected lines
+- `Enter` - Auto-continue lists with proper indentation
+
+### View & Navigation
 - `Ctrl/Cmd + P` - Toggle preview
 - `Ctrl/Cmd + Enter` - Toggle preview (alternative)
+- `Escape` - Close find dialog
 
 ## Building
 
 ```bash
+# Install dependencies
+npm install
+
+# Generate icons
+npm run generate-icons
+
 # Build for current platform
 npm run build
 
 # Build for specific platform
-npm run build:win
+npm run build:win    # Windows
-npm run build:mac
+npm run build:mac    # macOS  
-npm run build:linux
+npm run build:linux  # Linux (generates .deb, .AppImage, and .snap)
 
 # Build for all platforms
 npm run dist:all
 ```
 
+## Version History
+
+- **v1.3.0** - Major update: Tabbed interface for multiple files, enhanced PDF export with LaTeX engines, fixed file associations, removed redundant converter menu, improved UI architecture
+- **v1.2.1** - Comprehensive editor enhancements: Find & Replace, Line Numbers, Undo/Redo, Auto-indentation, PowerPoint export, document conversion menu, table creation helper, spreadsheet export
+- **v1.1.0** - Added Excel/ODS spreadsheet export, updated author information, renamed to PanConverter
+- **v1.0.0** - Initial release with basic markdown editing, themes, and Pandoc export
+
+## Known Issues
+
+- AppImage may require `--no-sandbox` flag on some Linux systems
+- Windows/Mac builds require platform-specific build environments
+- Large files may cause performance issues
+
 ## Contributing
 
-Contributions are welcome! Please feel free to submit a Pull Request.
+Contributions are welcome! Please feel free to submit a Pull Request to the [GitHub repository](https://github.com/amitwh/pan-converter).
 
 ## License
 
-MIT License - see LICENSE file for details
+MIT License - see LICENSE file for details.
+
+## Author
+
+**Amit Haridas** - [amit.wh@gmail.com](mailto:amit.wh@gmail.com)
 
 ## Acknowledgments
 
 - Built with [Electron](https://www.electronjs.org/)
 - Markdown parsing by [marked](https://marked.js.org/)
 - Export functionality powered by [Pandoc](https://pandoc.org/)
+- Syntax highlighting by [highlight.js](https://highlightjs.org/)
+- Spreadsheet export by [XLSX](https://www.npmjs.com/package/xlsx)
+- HTML sanitization by [DOMPurify](https://www.npmjs.com/package/dompurify)

package.json

@@ -1,6 +1,6 @@
 {
   "name": "pan-converter",
-  "version": "1.0.0",
+  "version": "1.3.1",
   "description": "Cross-platform Markdown editor and converter using Pandoc",
   "main": "src/main.js",
   "scripts": {
@@ -14,8 +14,13 @@
     "dist:all": "electron-builder -mwl",
     "generate-icons": "node scripts/generate-icons.js"
   },
-  "keywords": ["markdown", "pandoc", "converter", "editor"],
+  "keywords": [
-  "author": "Your Name",
+    "markdown",
+    "pandoc",
+    "converter",
+    "editor"
+  ],
+  "author": "Amit Haridas <amit.wh@gmail.com>",
   "license": "MIT",
   "devDependencies": {
     "electron": "^37.4.0",
@@ -27,11 +32,12 @@
     "dompurify": "^3.2.6",
     "electron-store": "^10.1.0",
     "highlight.js": "^11.11.1",
-    "marked": "^16.2.1"
+    "marked": "^16.2.1",
+    "xlsx": "^0.18.5"
   },
   "build": {
     "appId": "com.panconverter.app",
-    "productName": "Pan Converter",
+    "productName": "PanConverter",
     "directories": {
       "output": "dist"
     },
@@ -41,6 +47,22 @@
       "node_modules/**/*",
       "package.json"
     ],
+    "fileAssociations": [
+      {
+        "ext": "md",
+        "name": "Markdown Document",
+        "description": "Markdown Document",
+        "mimeType": "text/markdown",
+        "role": "Editor"
+      },
+      {
+        "ext": "markdown",
+        "name": "Markdown Document",
+        "description": "Markdown Document", 
+        "mimeType": "text/markdown",
+        "role": "Editor"
+      }
+    ],
     "mac": {
       "category": "public.app-category.productivity",
       "icon": "assets/icon.icns"
@@ -63,7 +85,7 @@
         "pandoc"
       ],
       "description": "Markdown editor and converter using Pandoc",
-      "maintainer": "Your Name <your.email@example.com>"
+      "maintainer": "Amit Haridas <amit.wh@gmail.com>"
     }
   }
 }

src/index.html

@@ -3,13 +3,20 @@
 <head>
     <meta charset="UTF-8">
     <meta name="viewport" content="width=device-width, initial-scale=1.0">
-    <title>Pan Converter - Markdown Editor</title>
+    <title>PanConverter - Markdown Editor</title>
     <link rel="stylesheet" href="styles.css">
     <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/codemirror/6.65.7/codemirror.min.css">
     <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/highlight.js/11.9.0/styles/default.min.css">
 </head>
 <body>
     <div class="container">
+        <div class="tab-bar" id="tab-bar">
+            <div class="tab active" data-tab-id="1">
+                <span class="tab-title">Untitled</span>
+                <button class="tab-close" title="Close tab">×</button>
+            </div>
+            <button class="new-tab-button" id="new-tab-btn" title="New tab">+</button>
+        </div>
         <div class="toolbar">
             <button id="btn-bold" title="Bold">
                 <svg width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2">
@@ -59,6 +66,29 @@
                     <path d="M15 21c3 0 7-1 7-8V5c0-1.25-.757-2.017-2-2h-4c-1.25 0-2 .75-2 1.972V11c0 1.25.75 2 2 2h.75c0 2.25.25 4-2.75 4v3c0 1 0 1 1 1z"></path>
                 </svg>
             </button>
+            <button id="btn-table" title="Insert Table">
+                <svg width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2">
+                    <rect x="3" y="3" width="18" height="18" rx="2" ry="2"></rect>
+                    <line x1="3" y1="9" x2="21" y2="9"></line>
+                    <line x1="3" y1="15" x2="21" y2="15"></line>
+                    <line x1="9" y1="3" x2="9" y2="21"></line>
+                    <line x1="15" y1="3" x2="15" y2="21"></line>
+                </svg>
+            </button>
+            <div class="toolbar-separator"></div>
+            <button id="btn-find" title="Find & Replace (Ctrl+F)">
+                <svg width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2">
+                    <circle cx="11" cy="11" r="8"></circle>
+                    <path d="m21 21-4.35-4.35"></path>
+                </svg>
+            </button>
+            <button id="btn-line-numbers" title="Toggle Line Numbers">
+                <svg width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2">
+                    <path d="M3 6h18"></path>
+                    <path d="M3 12h18"></path>
+                    <path d="M3 18h18"></path>
+                </svg>
+            </button>
             <div class="toolbar-separator"></div>
             <button id="btn-preview-toggle" title="Toggle Preview">
                 <svg width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2">
@@ -68,12 +98,33 @@
             </button>
         </div>
         
-        <div class="editor-container">
+        <!-- Find & Replace Dialog -->
-            <div id="editor-pane" class="pane">
+        <div id="find-dialog" class="find-dialog hidden">
-                <textarea id="editor"></textarea>
+            <div class="find-controls">
+                <input type="text" id="find-input" placeholder="Find...">
+                <input type="text" id="replace-input" placeholder="Replace...">
+                <button id="btn-find-prev" title="Previous">↑</button>
+                <button id="btn-find-next" title="Next">↓</button>
+                <button id="btn-replace" title="Replace">Replace</button>
+                <button id="btn-replace-all" title="Replace All">All</button>
+                <button id="btn-find-close" title="Close">×</button>
             </div>
-            <div id="preview-pane" class="pane">
+            <div class="find-info">
-                <div id="preview"></div>
+                <span id="find-count">0 matches</span>
+            </div>
+        </div>
+        
+        <div class="editor-container">
+            <div class="tab-content active" id="tab-content-1" data-tab-id="1">
+                <div id="editor-pane-1" class="pane">
+                    <div class="editor-wrapper">
+                        <div id="line-numbers-1" class="line-numbers hidden"></div>
+                        <textarea id="editor-1" class="editor-textarea"></textarea>
+                    </div>
+                </div>
+                <div id="preview-pane-1" class="pane">
+                    <div id="preview-1" class="preview-content"></div>
+                </div>
             </div>
         </div>
         

src/main.js

@@ -2,6 +2,7 @@ const { app, BrowserWindow, Menu, dialog, ipcMain, shell } = require('electron')
 const path = require('path');
 const fs = require('fs');
 const { exec } = require('child_process');
+const XLSX = require('xlsx');
 
 // Simple storage implementation to replace electron-store
 const settingsPath = path.join(app.getPath('userData'), 'settings.json');
@@ -27,7 +28,7 @@ const store = {
 };
 
 let mainWindow;
-let currentFile = null;
+let currentFile = null; // This will now represent the active tab's file
 
 function createWindow() {
   mainWindow = new BrowserWindow({
@@ -47,6 +48,14 @@ function createWindow() {
   mainWindow.on('closed', () => {
     mainWindow = null;
   });
+
+  // Handle pending file from file association
+  if (app.pendingFile) {
+    mainWindow.webContents.once('dom-ready', () => {
+      openFileFromPath(app.pendingFile);
+      app.pendingFile = null;
+    });
+  }
 }
 
 function createMenu() {
@@ -75,6 +84,11 @@ function createMenu() {
           click: saveAsFile
         },
         { type: 'separator' },
+        {
+          label: 'Import Document...',
+          accelerator: 'CmdOrCtrl+I',
+          click: importDocument
+        },
         {
           label: 'Export',
           submenu: [
@@ -84,7 +98,14 @@ function createMenu() {
             { label: 'LaTeX', click: () => exportFile('latex') },
             { label: 'RTF', click: () => exportFile('rtf') },
             { label: 'ODT', click: () => exportFile('odt') },
-            { label: 'EPUB', click: () => exportFile('epub') }
+            { label: 'EPUB', click: () => exportFile('epub') },
+            { type: 'separator' },
+            { label: 'PowerPoint (PPTX)', click: () => exportFile('pptx') },
+            { label: 'OpenDocument Presentation (ODP)', click: () => exportFile('odp') },
+            { type: 'separator' },
+            { label: 'Excel (XLSX)', click: () => exportSpreadsheet('xlsx') },
+            { label: 'Excel Legacy (XLS)', click: () => exportSpreadsheet('xls') },
+            { label: 'OpenDocument Spreadsheet (ODS)', click: () => exportSpreadsheet('ods') }
           ]
         },
         { type: 'separator' },
@@ -99,12 +120,18 @@ function createMenu() {
       label: 'Edit',
       submenu: [
         { label: 'Undo', accelerator: 'CmdOrCtrl+Z', role: 'undo' },
-        { label: 'Redo', accelerator: 'CmdOrCtrl+Y', role: 'redo' },
+        { label: 'Redo', accelerator: 'CmdOrCtrl+Shift+Z', role: 'redo' },
         { type: 'separator' },
         { label: 'Cut', accelerator: 'CmdOrCtrl+X', role: 'cut' },
         { label: 'Copy', accelerator: 'CmdOrCtrl+C', role: 'copy' },
         { label: 'Paste', accelerator: 'CmdOrCtrl+V', role: 'paste' },
-        { label: 'Select All', accelerator: 'CmdOrCtrl+A', role: 'selectAll' }
+        { label: 'Select All', accelerator: 'CmdOrCtrl+A', role: 'selectAll' },
+        { type: 'separator' },
+        { 
+          label: 'Find & Replace', 
+          accelerator: 'CmdOrCtrl+F', 
+          click: () => mainWindow.webContents.send('toggle-find') 
+        }
       ]
     },
     {
@@ -142,16 +169,16 @@ function createMenu() {
           click: () => {
             dialog.showMessageBox(mainWindow, {
               type: 'info',
-              title: 'About Pan Converter',
+              title: 'About PanConverter',
-              message: 'Pan Converter',
+              message: 'PanConverter',
-              detail: 'A cross-platform Markdown editor and converter using Pandoc.\n\nVersion: 1.0.0\nLicense: MIT',
+              detail: 'A cross-platform Markdown editor and converter using Pandoc.\n\nVersion: 1.3.1\nAuthor: Amit Haridas\nEmail: amit.wh@gmail.com\nLicense: MIT\n\nFeatures:\n• Tabbed interface for multiple files\n• Advanced markdown editing with live preview\n• Enhanced PDF export with LaTeX engines\n• File association support for .md files\n• Find & replace with match highlighting\n• Line numbers and auto-indentation\n• Export to multiple formats via Pandoc\n• PowerPoint & presentation export\n• Export tables to Excel/ODS spreadsheets\n• Document import & conversion\n• Table creation helper\n• Multiple themes support\n• Undo/redo functionality',
               buttons: ['OK']
             });
           }
         },
         {
           label: 'Documentation',
-          click: () => shell.openExternal('https://github.com/yourusername/pan-converter')
+          click: () => shell.openExternal('https://github.com/amitwh/pan-converter')
         }
       ]
     }
@@ -206,16 +233,102 @@ function exportFile(format) {
   });
 
   if (outputFile) {
-    const pandocCmd = `pandoc "${currentFile}" -o "${outputFile}"`;
+    let pandocCmd = `pandoc "${currentFile}" -o "${outputFile}"`;
+    
+    // Add specific options for PDF export to ensure proper generation
+    if (format === 'pdf') {
+      pandocCmd = `pandoc "${currentFile}" --pdf-engine=xelatex -V geometry:margin=1in -o "${outputFile}"`;
+      // Try with different PDF engines if xelatex fails
+      exec(pandocCmd, (error, stdout, stderr) => {
+        if (error) {
+          // Fallback to pdflatex
+          const fallbackCmd = `pandoc "${currentFile}" --pdf-engine=pdflatex -V geometry:margin=1in -o "${outputFile}"`;
+          exec(fallbackCmd, (fallbackError, fallbackStdout, fallbackStderr) => {
+            if (fallbackError) {
+              // Final fallback to wkhtmltopdf
+              const htmlToPdfCmd = `pandoc "${currentFile}" -t html5 | wkhtmltopdf - "${outputFile}"`;
+              exec(htmlToPdfCmd, (finalError) => {
+                if (finalError) {
+                  dialog.showErrorBox('PDF Export Error', 
+                    `Failed to export PDF. Please ensure you have one of the following installed:\n` +
+                    `• XeLaTeX (recommended): sudo apt-get install texlive-xetex\n` +
+                    `• PDFLaTeX: sudo apt-get install texlive-latex-base\n` +
+                    `• wkhtmltopdf: sudo apt-get install wkhtmltopdf\n\n` +
+                    `Error: ${finalError.message}`
+                  );
+                } else {
+                  showExportSuccess(outputFile);
+                }
+              });
+            } else {
+              showExportSuccess(outputFile);
+            }
+          });
+        } else {
+          showExportSuccess(outputFile);
+        }
+      });
+    } else {
+      exec(pandocCmd, (error, stdout, stderr) => {
+        if (error) {
+          dialog.showErrorBox('Export Error', `Failed to export: ${error.message}\n\nMake sure Pandoc is installed.`);
+        } else {
+          showExportSuccess(outputFile);
+        }
+      });
+    }
+  }
+}
+
+function showExportSuccess(outputFile) {
+  dialog.showMessageBox(mainWindow, {
+    type: 'info',
+    title: 'Export Complete',
+    message: `File exported successfully to ${outputFile}`,
+    buttons: ['OK']
+  });
+}
+
+function exportSpreadsheet(format) {
+  if (!currentFile) {
+    dialog.showErrorBox('Error', 'Please save the file first');
+    return;
+  }
+
+  // Request content from renderer
+  mainWindow.webContents.send('get-content-for-spreadsheet', format);
+}
+
+function importDocument() {
+  const files = dialog.showOpenDialogSync(mainWindow, {
+    properties: ['openFile'],
+    filters: [
+      { name: 'Documents', extensions: ['docx', 'odt', 'rtf', 'html', 'tex', 'epub', 'pdf'] },
+      { name: 'Presentations', extensions: ['pptx', 'odp'] },
+      { name: 'All Files', extensions: ['*'] }
+    ]
+  });
+
+  if (files && files[0]) {
+    const inputFile = files[0];
+    const outputFile = inputFile.replace(/\.[^/.]+$/, '.md');
+    
+    // Convert to markdown using pandoc
+    const pandocCmd = `pandoc "${inputFile}" -t markdown -o "${outputFile}"`;
     
     exec(pandocCmd, (error, stdout, stderr) => {
       if (error) {
-        dialog.showErrorBox('Export Error', `Failed to export: ${error.message}\n\nMake sure Pandoc is installed.`);
+        dialog.showErrorBox('Import Error', `Failed to import: ${error.message}\n\nMake sure Pandoc is installed.`);
       } else {
+        // Open the converted markdown file
+        currentFile = outputFile;
+        const content = fs.readFileSync(outputFile, 'utf-8');
+        mainWindow.webContents.send('file-opened', { path: outputFile, content });
+        
         dialog.showMessageBox(mainWindow, {
           type: 'info',
-          title: 'Export Complete',
+          title: 'Import Complete',
-          message: `File exported successfully to ${outputFile}`,
+          message: `Document imported successfully as ${outputFile}`,
           buttons: ['OK']
         });
       }
@@ -223,6 +336,7 @@ function exportFile(format) {
   }
 }
 
+
 function setTheme(theme) {
   store.set('theme', theme);
   mainWindow.webContents.send('theme-changed', theme);
@@ -247,7 +361,108 @@ ipcMain.on('get-theme', (event) => {
   event.reply('theme-changed', theme);
 });
 
-app.whenReady().then(createWindow);
+// Handle tab file tracking for exports
+ipcMain.on('set-current-file', (event, filePath) => {
+  currentFile = filePath;
+});
+
+ipcMain.on('export-spreadsheet', (event, { content, format }) => {
+  const outputFile = dialog.showSaveDialogSync(mainWindow, {
+    defaultPath: currentFile.replace(/\.[^/.]+$/, `.${format}`),
+    filters: [
+      { name: format.toUpperCase(), extensions: [format] }
+    ]
+  });
+
+  if (outputFile) {
+    try {
+      // Parse markdown content to extract tables
+      const tables = extractTablesFromMarkdown(content);
+      
+      if (tables.length === 0) {
+        dialog.showErrorBox('Export Error', 'No tables found in the markdown content');
+        return;
+      }
+
+      // Create workbook
+      const wb = XLSX.utils.book_new();
+      
+      tables.forEach((table, index) => {
+        const ws = XLSX.utils.aoa_to_sheet(table);
+        XLSX.utils.book_append_sheet(wb, ws, `Table ${index + 1}`);
+      });
+
+      // Write file
+      XLSX.writeFile(wb, outputFile);
+      
+      dialog.showMessageBox(mainWindow, {
+        type: 'info',
+        title: 'Export Complete',
+        message: `Spreadsheet exported successfully to ${outputFile}`,
+        buttons: ['OK']
+      });
+    } catch (error) {
+      dialog.showErrorBox('Export Error', `Failed to export: ${error.message}`);
+    }
+  }
+});
+
+// Helper function to extract tables from markdown
+function extractTablesFromMarkdown(markdown) {
+  const tables = [];
+  const lines = markdown.split('\n');
+  let currentTable = [];
+  let inTable = false;
+  
+  for (const line of lines) {
+    if (line.includes('|')) {
+      if (!inTable) {
+        inTable = true;
+        currentTable = [];
+      }
+      
+      // Skip separator lines (|---|---|)
+      if (!line.match(/^\s*\|?\s*:?-+:?\s*\|/)) {
+        const cells = line.split('|')
+          .map(cell => cell.trim())
+          .filter(cell => cell !== '');
+        
+        if (cells.length > 0) {
+          currentTable.push(cells);
+        }
+      }
+    } else if (inTable && line.trim() === '') {
+      // End of table
+      if (currentTable.length > 0) {
+        tables.push(currentTable);
+      }
+      currentTable = [];
+      inTable = false;
+    }
+  }
+  
+  // Add last table if exists
+  if (currentTable.length > 0) {
+    tables.push(currentTable);
+  }
+  
+  return tables;
+}
+
+app.whenReady().then(() => {
+  createWindow();
+  
+  // Handle file association on app startup
+  // Process all command line arguments except the first two (node and script path)
+  const fileArgs = process.argv.slice(2);
+  for (const arg of fileArgs) {
+    if ((arg.endsWith('.md') || arg.endsWith('.markdown')) && fs.existsSync(arg)) {
+      // Store the file to open after window is ready
+      app.pendingFile = arg;
+      break;
+    }
+  }
+});
 
 app.on('window-all-closed', () => {
   if (process.platform !== 'darwin') {
@@ -260,3 +475,25 @@ app.on('activate', () => {
     createWindow();
   }
 });
+
+// Handle file opening on macOS
+app.on('open-file', (event, filePath) => {
+  event.preventDefault();
+  if (mainWindow) {
+    openFileFromPath(filePath);
+  } else {
+    // Store the file path to open after window is created
+    app.pendingFile = filePath;
+  }
+});
+
+// Handle file opening from command line or file association
+function openFileFromPath(filePath) {
+  if (fs.existsSync(filePath)) {
+    currentFile = filePath;
+    const content = fs.readFileSync(filePath, 'utf-8');
+    if (mainWindow && mainWindow.webContents) {
+      mainWindow.webContents.send('file-opened', { path: filePath, content });
+    }
+  }
+}

src/renderer.js

@@ -17,202 +17,524 @@ marked.setOptions({
     gfm: true
 });
 
-// Elements
+// Tab Management
-const editor = document.getElementById('editor');
+class TabManager {
-const preview = document.getElementById('preview');
+    constructor() {
-const previewPane = document.getElementById('preview-pane');
+        this.tabs = new Map();
-const editorPane = document.getElementById('editor-pane');
+        this.activeTabId = 1;
-const statusText = document.getElementById('status-text');
+        this.nextTabId = 2;
-const wordCount = document.getElementById('word-count');
+        this.isPreviewVisible = true;
+        this.showLineNumbers = false;
         
-// State
+        // Initialize first tab
-let isPreviewVisible = true;
+        this.tabs.set(1, {
-let currentContent = '';
+            id: 1,
-let isDirty = false;
+            title: 'Untitled',
+            content: '',
+            filePath: null,
+            isDirty: false,
+            undoStack: [],
+            redoStack: [],
+            findMatches: [],
+            currentMatchIndex: -1
+        });
+        
+        this.setupEventListeners();
+        this.updateUI();
+    }
+    
+    setupEventListeners() {
+        // Tab bar events
+        document.getElementById('new-tab-btn').addEventListener('click', () => this.createNewTab());
+        document.getElementById('tab-bar').addEventListener('click', (e) => {
+            if (e.target.classList.contains('tab-close')) {
+                e.stopPropagation();
+                const tabId = parseInt(e.target.closest('.tab').dataset.tabId);
+                this.closeTab(tabId);
+            } else if (e.target.closest('.tab')) {
+                const tabId = parseInt(e.target.closest('.tab').dataset.tabId);
+                this.switchToTab(tabId);
+            }
+        });
+        
+        // Editor events for active tab
+        this.setupEditorEvents();
+        
+        // Toolbar events
+        this.setupToolbarEvents();
+        
+        // Find dialog events
+        this.setupFindEvents();
+        
+        // Keyboard shortcuts
+        document.addEventListener('keydown', (e) => {
+            if (e.ctrlKey || e.metaKey) {
+                switch (e.key) {
+                    case 'n':
+                        e.preventDefault();
+                        this.createNewTab();
+                        break;
+                    case 'w':
+                        if (this.tabs.size > 1) {
+                            e.preventDefault();
+                            this.closeTab(this.activeTabId);
+                        }
+                        break;
+                    case 't':
+                        e.preventDefault();
+                        this.createNewTab();
+                        break;
+                    case 'Tab':
+                        if (this.tabs.size > 1) {
+                            e.preventDefault();
+                            this.switchToNextTab();
+                        }
+                        break;
+                }
+            }
+        });
+    }
+    
+    createNewTab() {
+        const newTabId = this.nextTabId++;
+        const tab = {
+            id: newTabId,
+            title: 'Untitled',
+            content: '',
+            filePath: null,
+            isDirty: false,
+            undoStack: [],
+            redoStack: [],
+            findMatches: [],
+            currentMatchIndex: -1
+        };
+        
+        this.tabs.set(newTabId, tab);
+        this.createTabElements(tab);
+        this.switchToTab(newTabId);
+        this.updateTabBar();
+    }
+    
+    createTabElements(tab) {
+        // Create tab content container
+        const tabContent = document.createElement('div');
+        tabContent.className = 'tab-content';
+        tabContent.id = `tab-content-${tab.id}`;
+        tabContent.dataset.tabId = tab.id;
+        
+        tabContent.innerHTML = `
+            <div id="editor-pane-${tab.id}" class="pane">
+                <div class="editor-wrapper">
+                    <div id="line-numbers-${tab.id}" class="line-numbers hidden"></div>
+                    <textarea id="editor-${tab.id}" class="editor-textarea"></textarea>
+                </div>
+            </div>
+            <div id="preview-pane-${tab.id}" class="pane">
+                <div id="preview-${tab.id}" class="preview-content"></div>
+            </div>
+        `;
+        
+        document.querySelector('.editor-container').appendChild(tabContent);
+    }
+    
+    switchToTab(tabId) {
+        if (!this.tabs.has(tabId)) return;
+        
+        // Save current tab state before switching
+        if (this.activeTabId && this.tabs.has(this.activeTabId)) {
+            this.saveCurrentTabState();
+        }
+        
+        this.activeTabId = tabId;
+        this.updateUI();
+        this.restoreTabState(tabId);
+        this.focusActiveEditor();
+        
+        // Notify main process about current file for exports
+        const tab = this.tabs.get(tabId);
+        if (tab && tab.filePath) {
+            ipcRenderer.send('set-current-file', tab.filePath);
+        }
+    }
+    
+    switchToNextTab() {
+        const tabIds = Array.from(this.tabs.keys());
+        const currentIndex = tabIds.indexOf(this.activeTabId);
+        const nextIndex = (currentIndex + 1) % tabIds.length;
+        this.switchToTab(tabIds[nextIndex]);
+    }
+    
+    closeTab(tabId) {
+        if (this.tabs.size === 1) return; // Don't close the last tab
+        
+        const tab = this.tabs.get(tabId);
+        if (tab.isDirty) {
+            // TODO: Show confirmation dialog
+        }
+        
+        // Remove tab elements
+        const tabElement = document.querySelector(`[data-tab-id="${tabId}"]`);
+        const tabContent = document.getElementById(`tab-content-${tabId}`);
+        
+        if (tabElement && tabElement.classList.contains('tab')) {
+            tabElement.remove();
+        }
+        if (tabContent) {
+            tabContent.remove();
+        }
+        
+        this.tabs.delete(tabId);
+        
+        // Switch to another tab if this was active
+        if (this.activeTabId === tabId) {
+            const remainingTabs = Array.from(this.tabs.keys());
+            this.switchToTab(remainingTabs[0]);
+        }
+        
+        this.updateTabBar();
+    }
+    
+    updateTabBar() {
+        const tabBar = document.getElementById('tab-bar');
+        const existingTabs = tabBar.querySelectorAll('.tab');
+        
+        // Remove all existing tab elements except the new tab button
+        existingTabs.forEach(tab => tab.remove());
+        
+        // Add tabs in order
+        const sortedTabs = Array.from(this.tabs.values()).sort((a, b) => a.id - b.id);
+        const newTabBtn = document.getElementById('new-tab-btn');
+        
+        sortedTabs.forEach(tab => {
+            const tabElement = document.createElement('div');
+            tabElement.className = `tab ${tab.id === this.activeTabId ? 'active' : ''}`;
+            tabElement.dataset.tabId = tab.id;
+            
+            const title = tab.filePath ? 
+                tab.filePath.split('/').pop() : 
+                tab.title;
+                
+            const dirtyIndicator = tab.isDirty ? ' •' : '';
+            
+            tabElement.innerHTML = `
+                <span class="tab-title">${title}${dirtyIndicator}</span>
+                <button class="tab-close" title="Close tab">×</button>
+            `;
+            
+            tabBar.insertBefore(tabElement, newTabBtn);
+        });
+    }
+    
+    updateUI() {
+        // Show/hide tab contents
+        document.querySelectorAll('.tab-content').forEach(content => {
+            content.classList.remove('active');
+        });
+        
+        const activeContent = document.getElementById(`tab-content-${this.activeTabId}`);
+        if (activeContent) {
+            activeContent.classList.add('active');
+        }
+        
+        // Update preview visibility
+        this.updatePreviewVisibility();
+        this.updateLineNumbers();
+        this.updateTabBar();
+    }
+    
+    saveCurrentTabState() {
+        const tab = this.tabs.get(this.activeTabId);
+        if (!tab) return;
+        
+        const editor = document.getElementById(`editor-${this.activeTabId}`);
+        if (editor) {
+            tab.content = editor.value;
+            tab.isDirty = tab.content !== (tab.originalContent || '');
+        }
+    }
+    
+    restoreTabState(tabId) {
+        const tab = this.tabs.get(tabId);
+        if (!tab) return;
+        
+        const editor = document.getElementById(`editor-${tabId}`);
+        const preview = document.getElementById(`preview-${tabId}`);
+        
+        if (editor) {
+            editor.value = tab.content;
+            this.updatePreview(tabId);
+            this.updateWordCount();
+        }
+    }
+    
+    focusActiveEditor() {
+        const editor = document.getElementById(`editor-${this.activeTabId}`);
+        if (editor) {
+            editor.focus();
+        }
+    }
+    
+    updatePreview(tabId = this.activeTabId) {
+        const tab = this.tabs.get(tabId);
+        const preview = document.getElementById(`preview-${tabId}`);
+        
+        if (!tab || !preview) return;
+        
+        try {
+            const html = marked.parse(tab.content);
+            const sanitizedHtml = DOMPurify.sanitize(html);
+            preview.innerHTML = sanitizedHtml;
+        } catch (error) {
+            preview.innerHTML = '<p>Error rendering preview</p>';
+        }
+    }
+    
+    updatePreviewVisibility() {
+        document.querySelectorAll('.tab-content').forEach(content => {
+            const previewPane = content.querySelector('.pane:last-child');
+            const editorPane = content.querySelector('.pane:first-child');
+            
+            if (this.isPreviewVisible) {
+                previewPane.classList.remove('hidden');
+                editorPane.classList.remove('full-width');
+            } else {
+                previewPane.classList.add('hidden');
+                editorPane.classList.add('full-width');
+            }
+        });
+    }
+    
+    updateLineNumbers() {
+        const editor = document.getElementById(`editor-${this.activeTabId}`);
+        const lineNumbers = document.getElementById(`line-numbers-${this.activeTabId}`);
+        
+        if (!editor || !lineNumbers) return;
+        
+        if (this.showLineNumbers) {
+            const lines = editor.value.split('\\n');
+            lineNumbers.innerHTML = lines.map((_, i) => 
+                `<div class="line-number">${i + 1}</div>`
+            ).join('');
+            lineNumbers.classList.remove('hidden');
+        } else {
+            lineNumbers.classList.add('hidden');
+        }
+    }
+    
+    updateWordCount() {
+        const tab = this.tabs.get(this.activeTabId);
+        if (!tab) return;
+        
+        const words = tab.content.trim().split(/\\s+/).filter(word => word.length > 0).length;
+        const chars = tab.content.length;
+        document.getElementById('word-count').textContent = `Words: ${words} | Characters: ${chars}`;
+    }
+    
+    setupEditorEvents() {
+        // Set up editor events using event delegation
+        document.addEventListener('input', (e) => {
+            if (e.target.classList.contains('editor-textarea')) {
+                const tabId = parseInt(e.target.id.split('-')[1]);
+                if (tabId === this.activeTabId) {
+                    this.handleEditorInput(tabId);
+                }
+            }
+        });
+        
+        document.addEventListener('scroll', (e) => {
+            if (e.target.classList.contains('editor-textarea')) {
+                const tabId = parseInt(e.target.id.split('-')[1]);
+                if (tabId === this.activeTabId) {
+                    this.updateLineNumbers();
+                }
+            }
+        });
+    }
+    
+    handleEditorInput(tabId) {
+        const tab = this.tabs.get(tabId);
+        if (!tab) return;
+        
+        const editor = document.getElementById(`editor-${tabId}`);
+        tab.content = editor.value;
+        tab.isDirty = true;
+        
+        this.updatePreview(tabId);
+        this.updateWordCount();
+        this.updateLineNumbers();
+        this.updateTabBar();
+        
+        // Add to undo stack
+        this.pushUndoState(tabId);
+    }
+    
+    pushUndoState(tabId) {
+        const tab = this.tabs.get(tabId);
+        if (!tab) return;
+        
+        tab.undoStack.push(tab.content);
+        if (tab.undoStack.length > 50) {
+            tab.undoStack.shift();
+        }
+        tab.redoStack = [];
+    }
+    
+    undo() {
+        const tab = this.tabs.get(this.activeTabId);
+        if (!tab || tab.undoStack.length === 0) return;
+        
+        tab.redoStack.push(tab.content);
+        tab.content = tab.undoStack.pop();
+        
+        const editor = document.getElementById(`editor-${this.activeTabId}`);
+        if (editor) {
+            editor.value = tab.content;
+            this.updatePreview();
+            this.updateWordCount();
+        }
+    }
+    
+    redo() {
+        const tab = this.tabs.get(this.activeTabId);
+        if (!tab || tab.redoStack.length === 0) return;
+        
+        tab.undoStack.push(tab.content);
+        tab.content = tab.redoStack.pop();
+        
+        const editor = document.getElementById(`editor-${this.activeTabId}`);
+        if (editor) {
+            editor.value = tab.content;
+            this.updatePreview();
+            this.updateWordCount();
+        }
+    }
+    
+    setupToolbarEvents() {
+        // Existing toolbar setup...
+        document.getElementById('btn-preview-toggle').addEventListener('click', () => {
+            this.isPreviewVisible = !this.isPreviewVisible;
+            this.updatePreviewVisibility();
+        });
+        
+        document.getElementById('btn-line-numbers').addEventListener('click', () => {
+            this.showLineNumbers = !this.showLineNumbers;
+            this.updateLineNumbers();
+        });
+        
+        // Add other toolbar events...
+    }
+    
+    setupFindEvents() {
+        // Find dialog implementation...
+        document.getElementById('btn-find').addEventListener('click', () => {
+            document.getElementById('find-dialog').classList.remove('hidden');
+            document.getElementById('find-input').focus();
+        });
+        
+        document.getElementById('btn-find-close').addEventListener('click', () => {
+            document.getElementById('find-dialog').classList.add('hidden');
+        });
+    }
+    
+    // File operations
+    openFile(filePath, content) {
+        let tab = this.tabs.get(this.activeTabId);
+        
+        // If current tab is empty and untitled, reuse it
+        if (!tab.filePath && !tab.isDirty && tab.content === '') {
+            tab.filePath = filePath;
+            tab.title = filePath.split('/').pop();
+            tab.content = content;
+            tab.originalContent = content;
+            tab.isDirty = false;
+        } else {
+            // Create new tab for the file
+            this.createNewTab();
+            tab = this.tabs.get(this.activeTabId);
+            tab.filePath = filePath;
+            tab.title = filePath.split('/').pop();
+            tab.content = content;
+            tab.originalContent = content;
+            tab.isDirty = false;
+        }
+        
+        this.restoreTabState(this.activeTabId);
+        this.updateTabBar();
+    }
+    
+    getCurrentContent() {
+        const tab = this.tabs.get(this.activeTabId);
+        return tab ? tab.content : '';
+    }
+    
+    getCurrentFilePath() {
+        const tab = this.tabs.get(this.activeTabId);
+        return tab ? tab.filePath : null;
+    }
+}
+
+// Initialize tab manager
+let tabManager;
 
-// Initialize
 document.addEventListener('DOMContentLoaded', () => {
+    tabManager = new TabManager();
+    
     // Request current theme
     ipcRenderer.send('get-theme');
     
     // Set up auto-save interval
-    setInterval(autoSave, 30000); // Auto-save every 30 seconds
+    setInterval(() => {
-    
+        // Auto-save logic for all tabs
-    // Initialize with empty content
+        tabManager.tabs.forEach(tab => {
-    updatePreview();
+            if (tab.isDirty && tab.filePath) {
-    updateWordCount();
+                ipcRenderer.send('save-current-file', tab.content);
+            }
+        });
+    }, 30000);
 });
 
-// Editor input handler
+// IPC event listeners
-editor.addEventListener('input', () => {
-    currentContent = editor.value;
-    isDirty = true;
-    updatePreview();
-    updateWordCount();
-    updateStatus('Modified');
-});
-
-// Toolbar button handlers
-document.getElementById('btn-bold').addEventListener('click', () => insertMarkdown('**', '**'));
-document.getElementById('btn-italic').addEventListener('click', () => insertMarkdown('*', '*'));
-document.getElementById('btn-heading').addEventListener('click', () => insertMarkdown('## ', ''));
-document.getElementById('btn-link').addEventListener('click', () => insertMarkdown('[', '](url)'));
-document.getElementById('btn-code').addEventListener('click', () => insertMarkdown('`', '`'));
-document.getElementById('btn-list').addEventListener('click', () => insertMarkdown('- ', ''));
-document.getElementById('btn-quote').addEventListener('click', () => insertMarkdown('> ', ''));
-document.getElementById('btn-preview-toggle').addEventListener('click', togglePreview);
-
-// Markdown insertion helper
-function insertMarkdown(before, after) {
-    const start = editor.selectionStart;
-    const end = editor.selectionEnd;
-    const selectedText = editor.value.substring(start, end);
-    const replacement = before + (selectedText || 'text') + after;
-    
-    editor.value = editor.value.substring(0, start) + replacement + editor.value.substring(end);
-    
-    // Set cursor position
-    if (selectedText) {
-        editor.selectionStart = start;
-        editor.selectionEnd = start + replacement.length;
-    } else {
-        editor.selectionStart = start + before.length;
-        editor.selectionEnd = start + before.length + 4; // Select "text"
-    }
-    
-    editor.focus();
-    
-    // Trigger input event
-    editor.dispatchEvent(new Event('input'));
-}
-
-// Update preview
-function updatePreview() {
-    const html = marked.parse(editor.value);
-    const clean = DOMPurify.sanitize(html);
-    preview.innerHTML = clean;
-    
-    // Re-highlight code blocks
-    preview.querySelectorAll('pre code').forEach((block) => {
-        hljs.highlightElement(block);
-    });
-}
-
-// Toggle preview visibility
-function togglePreview() {
-    isPreviewVisible = !isPreviewVisible;
-    
-    if (isPreviewVisible) {
-        previewPane.classList.remove('hidden');
-        editorPane.classList.remove('full-width');
-    } else {
-        previewPane.classList.add('hidden');
-        editorPane.classList.add('full-width');
-    }
-}
-
-// Update word count
-function updateWordCount() {
-    const text = editor.value;
-    const words = text.trim() ? text.trim().split(/\s+/).length : 0;
-    const chars = text.length;
-    wordCount.textContent = `Words: ${words} | Characters: ${chars}`;
-}
-
-// Update status
-function updateStatus(text) {
-    statusText.textContent = text;
-}
-
-// Auto-save function
-function autoSave() {
-    if (isDirty && currentContent) {
-        ipcRenderer.send('save-current-file', currentContent);
-        isDirty = false;
-        updateStatus('Auto-saved');
-        setTimeout(() => updateStatus('Ready'), 2000);
-    }
-}
-
-// IPC event handlers
 ipcRenderer.on('file-new', () => {
-    if (isDirty) {
+    tabManager.createNewTab();
-        if (confirm('You have unsaved changes. Do you want to continue?')) {
-            editor.value = '';
-            currentContent = '';
-            isDirty = false;
-            updatePreview();
-            updateWordCount();
-            updateStatus('New file');
-        }
-    } else {
-        editor.value = '';
-        currentContent = '';
-        updatePreview();
-        updateWordCount();
-        updateStatus('New file');
-    }
 });
 
-ipcRenderer.on('file-opened', (event, { path, content }) => {
+ipcRenderer.on('file-opened', (event, data) => {
-    editor.value = content;
+    tabManager.openFile(data.path, data.content);
-    currentContent = content;
-    isDirty = false;
-    updatePreview();
-    updateWordCount();
-    updateStatus(`Opened: ${path}`);
 });
 
 ipcRenderer.on('file-save', () => {
-    ipcRenderer.send('save-current-file', editor.value);
+    const currentContent = tabManager.getCurrentContent();
-    isDirty = false;
+    const currentFilePath = tabManager.getCurrentFilePath();
-    updateStatus('Saved');
+    if (currentFilePath) {
+        ipcRenderer.send('save-current-file', currentContent);
+    }
 });
 
-ipcRenderer.on('get-content-for-save', (event, path) => {
+ipcRenderer.on('get-content-for-save', (event, filePath) => {
-    ipcRenderer.send('save-file', { path, content: editor.value });
+    const currentContent = tabManager.getCurrentContent();
-    isDirty = false;
+    ipcRenderer.send('save-file', { path: filePath, content: currentContent });
-    updateStatus(`Saved: ${path}`);
+});
+
+ipcRenderer.on('get-content-for-spreadsheet', (event, format) => {
+    const currentContent = tabManager.getCurrentContent();
+    ipcRenderer.send('export-spreadsheet', { content: currentContent, format });
 });
 
 ipcRenderer.on('toggle-preview', () => {
-    togglePreview();
+    tabManager.isPreviewVisible = !tabManager.isPreviewVisible;
+    tabManager.updatePreviewVisibility();
+});
+
+ipcRenderer.on('toggle-find', () => {
+    const findDialog = document.getElementById('find-dialog');
+    if (findDialog.classList.contains('hidden')) {
+        findDialog.classList.remove('hidden');
+        document.getElementById('find-input').focus();
+    } else {
+        findDialog.classList.add('hidden');
+    }
 });
 
 ipcRenderer.on('theme-changed', (event, theme) => {
-    // Remove all theme classes
+    document.body.className = `theme-${theme}`;
-    document.body.classList.remove('theme-light', 'theme-dark', 'theme-solarized', 'theme-monokai', 'theme-github');
-    
-    // Add new theme class
-    if (theme !== 'light') {
-        document.body.classList.add(`theme-${theme}`);
-    }
-    
-    updateStatus(`Theme: ${theme}`);
-});
-
-// Keyboard shortcuts
-document.addEventListener('keydown', (e) => {
-    // Ctrl/Cmd + Enter to toggle preview
-    if ((e.ctrlKey || e.metaKey) && e.key === 'Enter') {
-        togglePreview();
-    }
-    
-    // Tab key in editor
-    if (e.key === 'Tab' && e.target === editor) {
-        e.preventDefault();
-        const start = editor.selectionStart;
-        const end = editor.selectionEnd;
-        
-        editor.value = editor.value.substring(0, start) + '    ' + editor.value.substring(end);
-        editor.selectionStart = editor.selectionEnd = start + 4;
-    }
-});
-
-// Prevent accidental navigation
-window.addEventListener('beforeunload', (e) => {
-    if (isDirty) {
-        e.preventDefault();
-        e.returnValue = '';
-    }
 });

src/styles.css

@@ -16,6 +16,93 @@ body {
     height: 100vh;
 }
 
+/* Tab Bar */
+.tab-bar {
+    display: flex;
+    align-items: center;
+    background: #f0f0f0;
+    border-bottom: 1px solid #ddd;
+    padding: 0 8px;
+    min-height: 36px;
+}
+
+.tab {
+    display: flex;
+    align-items: center;
+    padding: 6px 12px;
+    background: #e8e8e8;
+    border: 1px solid #ccc;
+    border-bottom: none;
+    border-radius: 6px 6px 0 0;
+    margin-right: 2px;
+    cursor: pointer;
+    user-select: none;
+    max-width: 200px;
+    min-width: 120px;
+}
+
+.tab.active {
+    background: #fff;
+    border-color: #999;
+    z-index: 1;
+}
+
+.tab-title {
+    flex: 1;
+    overflow: hidden;
+    text-overflow: ellipsis;
+    white-space: nowrap;
+    font-size: 13px;
+}
+
+.tab-close {
+    background: none;
+    border: none;
+    font-size: 16px;
+    font-weight: bold;
+    cursor: pointer;
+    padding: 0;
+    margin-left: 8px;
+    width: 16px;
+    height: 16px;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    border-radius: 3px;
+    color: #666;
+}
+
+.tab-close:hover {
+    background: #ddd;
+    color: #000;
+}
+
+.new-tab-button {
+    background: none;
+    border: 1px solid #ccc;
+    border-radius: 4px;
+    padding: 4px 8px;
+    cursor: pointer;
+    font-size: 14px;
+    margin-left: 8px;
+    color: #666;
+}
+
+.new-tab-button:hover {
+    background: #e8e8e8;
+}
+
+/* Tab Content */
+.tab-content {
+    display: flex;
+    flex: 1;
+    overflow: hidden;
+}
+
+.tab-content:not(.active) {
+    display: none;
+}
+
 /* Toolbar */
 .toolbar {
     display: flex;
@@ -65,8 +152,36 @@ body {
 .pane {
     flex: 1;
     overflow: auto;
+    min-width: 0;
 }
 
+.pane:first-child {
+    border-right: 1px solid #ddd;
+}
+
+.editor-textarea {
+    width: 100%;
+    height: 100%;
+    padding: 20px;
+    font-family: 'SF Mono', Monaco, 'Courier New', monospace;
+    font-size: 14px;
+    line-height: 1.6;
+    border: none;
+    outline: none;
+    resize: none;
+}
+
+.pane:last-child {
+    padding: 20px;
+    background: #fff;
+}
+
+.preview-content {
+    max-width: 800px;
+    margin: 0 auto;
+}
+
+/* Legacy support for old selectors */
 #editor-pane {
     border-right: 1px solid #ddd;
 }
@@ -217,6 +332,40 @@ body.theme-dark {
     color: #d4d4d4;
 }
 
+body.theme-dark .tab-bar {
+    background: #2d2d30;
+    border-bottom-color: #3e3e42;
+}
+
+body.theme-dark .tab {
+    background: #3c3c3c;
+    border-color: #555;
+    color: #d4d4d4;
+}
+
+body.theme-dark .tab.active {
+    background: #1e1e1e;
+    border-color: #666;
+}
+
+body.theme-dark .tab-close {
+    color: #ccc;
+}
+
+body.theme-dark .tab-close:hover {
+    background: #555;
+    color: #fff;
+}
+
+body.theme-dark .new-tab-button {
+    border-color: #555;
+    color: #ccc;
+}
+
+body.theme-dark .new-tab-button:hover {
+    background: #3c3c3c;
+}
+
 body.theme-dark .toolbar {
     background: #2d2d30;
     border-bottom-color: #3e3e42;
@@ -235,6 +384,20 @@ body.theme-dark .toolbar-separator {
     background: #3e3e42;
 }
 
+body.theme-dark .pane:first-child {
+    border-right-color: #3e3e42;
+}
+
+body.theme-dark .editor-textarea {
+    background: #1e1e1e;
+    color: #d4d4d4;
+}
+
+body.theme-dark .pane:last-child {
+    background: #252526;
+}
+
+/* Legacy support */
 body.theme-dark #editor-pane {
     border-right-color: #3e3e42;
 }
@@ -453,6 +616,15 @@ body.theme-github .status-bar {
 }
 
 /* Hide preview pane by default */
+.pane.hidden {
+    display: none;
+}
+
+.pane.full-width {
+    border-right: none;
+}
+
+/* Legacy support */
 #preview-pane.hidden {
     display: none;
 }
@@ -460,3 +632,139 @@ body.theme-github .status-bar {
 #editor-pane.full-width {
     border-right: none;
 }
+
+/* Find & Replace Dialog */
+.find-dialog {
+    position: absolute;
+    top: 60px;
+    right: 20px;
+    background: #fff;
+    border: 1px solid #ddd;
+    border-radius: 6px;
+    box-shadow: 0 4px 12px rgba(0,0,0,0.15);
+    z-index: 1000;
+    min-width: 400px;
+    padding: 12px;
+}
+
+.find-dialog.hidden {
+    display: none;
+}
+
+.find-controls {
+    display: flex;
+    align-items: center;
+    gap: 6px;
+    margin-bottom: 8px;
+}
+
+.find-controls input {
+    flex: 1;
+    padding: 6px 8px;
+    border: 1px solid #ddd;
+    border-radius: 4px;
+    font-size: 13px;
+}
+
+.find-controls button {
+    padding: 6px 10px;
+    border: 1px solid #ddd;
+    background: #f5f5f5;
+    border-radius: 4px;
+    cursor: pointer;
+    font-size: 12px;
+    white-space: nowrap;
+}
+
+.find-controls button:hover {
+    background: #e5e5e5;
+}
+
+.find-info {
+    font-size: 12px;
+    color: #666;
+    text-align: right;
+}
+
+/* Editor Wrapper with Line Numbers */
+.editor-wrapper {
+    position: relative;
+    display: flex;
+    height: 100%;
+}
+
+.line-numbers {
+    min-width: 40px;
+    padding: 8px 4px;
+    background: #f8f8f8;
+    border-right: 1px solid #ddd;
+    font-family: 'Monaco', 'Menlo', 'Ubuntu Mono', monospace;
+    font-size: 13px;
+    line-height: 1.4;
+    color: #666;
+    text-align: right;
+    user-select: none;
+    overflow: hidden;
+}
+
+.line-numbers.hidden {
+    display: none;
+}
+
+.line-numbers .line-number {
+    display: block;
+    white-space: nowrap;
+}
+
+/* Adjust editor when line numbers are shown */
+.editor-wrapper #editor {
+    flex: 1;
+}
+
+/* Theme support for find dialog */
+body.theme-dark .find-dialog {
+    background: #2d2d2d;
+    border-color: #555;
+    color: #f0f0f0;
+}
+
+body.theme-dark .find-controls input {
+    background: #333;
+    border-color: #555;
+    color: #f0f0f0;
+}
+
+body.theme-dark .find-controls button {
+    background: #404040;
+    border-color: #555;
+    color: #f0f0f0;
+}
+
+body.theme-dark .find-controls button:hover {
+    background: #4a4a4a;
+}
+
+body.theme-dark .line-numbers {
+    background: #2a2a2a;
+    border-right-color: #555;
+    color: #888;
+}
+
+/* Additional theme support for line numbers */
+body.theme-solarized .line-numbers {
+    background: #fdf6e3;
+    border-right-color: #eee8d5;
+    color: #93a1a1;
+}
+
+body.theme-monokai .line-numbers {
+    background: #2f2f2f;
+    border-right-color: #555;
+    color: #75715e;
+}
+
+body.theme-github .line-numbers {
+    background: #fafbfc;
+    border-right-color: #e1e4e8;
+    color: #586069;
+}