Refactor _removeLastZone to avoid recreating entire editor

Simplified the _removeLastZone() function to be more efficient:

Before:
- Removed last zone from array
- Destroyed and recreated entire editor interface (_cancelEditor + startEditor)
- Recreated all remaining zones from scratch
- Caused visual flicker and was inefficient
- Could leave dangling event listeners

After:
- Remove last zone from zones array
- Remove and destroy only the last zone actor
- No need to update zone numbers (removing last zone doesn't affect other numbers)
- No editor recreation needed

Benefits:
- No visual flicker
- Much more efficient (O(1) instead of O(n))
- Cleaner code (15 lines vs 50+ lines)
- No risk of dangling event listeners from recreation
- Better user experience

Fixes TODO item #2.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

TODO.md

@@ -11,13 +11,13 @@
 - [x] Save layouts when created in graphical editor
 - [x] Load layouts on extension initialization
 
-### 2. Remove Last Zone Implementation (extension.js:236-274)
+### 2. Remove Last Zone Implementation ✅ COMPLETED
 **Priority: Medium**
-- [ ] `_removeLastZone()` destroys and recreates entire editor interface
-- [ ] Causes visual flicker
-- [ ] Inefficient approach
-- [ ] Could leave dangling event listeners
-- [ ] Refactor to only remove the last zone widget without recreating everything
+- [x] `_removeLastZone()` destroys and recreates entire editor interface
+- [x] Causes visual flicker
+- [x] Inefficient approach
+- [x] Could leave dangling event listeners
+- [x] Refactor to only remove the last zone widget without recreating everything
 
 ## Functionality Improvements
 

extension.js

@@ -548,53 +548,20 @@ ZoneEditor.prototype = {
     
     _removeLastZone: function() {
         if (this.zones.length > 0) {
+            // Remove the last zone from data
             this.zones.pop();
 
-            // Also remove the last zone actor
+            // Remove and destroy the last zone actor
             if (this.zoneActors.length > 0) {
                 let removedActor = this.zoneActors.pop();
                 this.editorOverlay.remove_child(removedActor);
                 removedActor.destroy();
             }
 
-            // Redraw editor
-            this._cancelEditor();
-            this.startEditor();
-
-            // Re-add existing zones
-            let monitor = Main.layoutManager.primaryMonitor;
-            this.zoneActors = [];  // Reset actors array
-            this.zones.forEach((zone, index) => {
-                let zoneActor = new St.Widget({
-                    style_class: 'gridsnap-editor-zone',
-                    x: zone.x * monitor.width,
-                    y: zone.y * monitor.height,
-                    width: zone.width * monitor.width,
-                    height: zone.height * monitor.height
-                });
-                zoneActor.set_style(
-                    'border: 3px solid rgba(100, 255, 100, 0.9);' +
-                    'background-color: rgba(100, 255, 100, 0.3);' +
-                    'border-radius: 4px;'
-                );
-
-                let label = new St.Label({
-                    text: String(index + 1),
-                    x: 10,
-                    y: 10
-                });
-                label.set_style(
-                    'color: white;' +
-                    'font-size: 24px;' +
-                    'font-weight: bold;' +
-                    'text-shadow: 2px 2px 4px rgba(0,0,0,0.8);'
-                );
-                zoneActor.add_child(label);
-                this.editorOverlay.add_child(zoneActor);
-
-                // Track zone actors for moving
-                this.zoneActors.push(zoneActor);
-            });
+            // Update zone numbers on remaining zones
+            // Since we removed the last zone, we only need to update if there are still zones
+            // The numbering is 1-indexed, so zone 0 displays "1", zone 1 displays "2", etc.
+            // No need to update numbers since we removed the last one - other numbers stay the same
         }
     },