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

package.json

@@ -1,6 +1,6 @@
 {
   "name": "pan-converter",
-  "version": "1.3.0",
+  "version": "1.3.1",
   "description": "Cross-platform Markdown editor and converter using Pandoc",
   "main": "src/main.js",
   "scripts": {
@@ -47,6 +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"

src/main.js

@@ -171,7 +171,7 @@ function createMenu() {
               type: 'info',
               title: 'About PanConverter',
               message: 'PanConverter',
-              detail: 'A cross-platform Markdown editor and converter using Pandoc.\n\nVersion: 1.3.0\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• 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',
+              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']
             });
           }
@@ -453,10 +453,13 @@ app.whenReady().then(() => {
   createWindow();
   
   // Handle file association on app startup
-  if (process.argv.length > 1) {
-    const filePath = process.argv.find(arg => arg.endsWith('.md') || arg.endsWith('.markdown'));
-    if (filePath && fs.existsSync(filePath)) {
-      openFileFromPath(filePath);
+  // 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;
     }
   }
 });

src/styles.css

@@ -152,8 +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;
 }
@@ -356,6 +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;
 }
@@ -574,6 +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;
 }