Fire onSelectionChange when starting to drag

src/browser/services/SelectionService.test.ts

@@ -496,5 +496,19 @@ describe('SelectionService', () => {
       assert.isFalse(selectionService.areCoordsInSelection([2, 1], [2, 0], [2, 1]));
     });
   });
+
+  describe('onSelectionChange', () => {
+    it('should not fire when setting model properties directly', () => {
+      buffer.lines.set(0, stringToRow('foo bar'));
+
+      let eventFired = false;
+      selectionService.onSelectionChange(() => { eventFired = true; });
+
+      selectionService.model.selectionStart = [0, 0];
+      selectionService.model.selectionEnd = undefined;
+
+      assert.isFalse(eventFired);
+    });
+  });
 });
 

src/browser/services/SelectionService.ts

@@ -532,6 +532,9 @@ export class SelectionService extends Disposable implements ISelectionService {
    * @param event The mouse event.
    */
   private _handleSingleClick(event: MouseEvent): void {
+    // Track if there was a selection before clearing
+    const hadSelection = this.hasSelection;
+
     this._model.selectionStartLength = 0;
     this._model.isSelectAllActive = false;
     this._activeSelectionMode = this.shouldColumnSelect(event) ? SelectionMode.COLUMN : SelectionMode.NORMAL;
@@ -543,6 +546,11 @@ export class SelectionService extends Disposable implements ISelectionService {
     }
     this._model.selectionEnd = undefined;
 
+    // Fire selection change event if a selection was cleared
+    if (hadSelection) {
+      this._fireOnSelectionChange(this._model.finalSelectionStart, this._model.finalSelectionEnd, false);
+    }
+
     // Ensure the line exists
     const line = this._bufferService.buffer.lines.get(this._model.selectionStart[1]);
     if (!line) {