Focus editor for tab after dragged over for 1500 millis (#149604)

* Focus editor for tab after dragged over for 1500 millis

* 💄

Co-authored-by: Benjamin Pasero <benjamin.pasero@gmail.com>

src/vs/base/browser/dom.ts

@@ -1702,8 +1702,7 @@ export interface IDragAndDropObserverCallbacks {
 	readonly onDragLeave: (e: DragEvent) => void;
 	readonly onDrop: (e: DragEvent) => void;
 	readonly onDragEnd: (e: DragEvent) => void;
-
-	readonly onDragOver?: (e: DragEvent) => void;
+	readonly onDragOver?: (e: DragEvent, dragDuration: number) => void;
 }
 
 export class DragAndDropObserver extends Disposable {
@@ -1714,6 +1713,9 @@ export class DragAndDropObserver extends Disposable {
 	// repeadedly.
 	private counter: number = 0;
 
+	// Allows to measure the duration of the drag operation.
+	private dragStartTime = 0;
+
 	constructor(private readonly element: HTMLElement, private readonly callbacks: IDragAndDropObserverCallbacks) {
 		super();
 
@@ -1723,6 +1725,7 @@ export class DragAndDropObserver extends Disposable {
 	private registerListeners(): void {
 		this._register(addDisposableListener(this.element, EventType.DRAG_ENTER, (e: DragEvent) => {
 			this.counter++;
+			this.dragStartTime = e.timeStamp;
 
 			this.callbacks.onDragEnter(e);
 		}));
@@ -1731,7 +1734,7 @@ export class DragAndDropObserver extends Disposable {
 			e.preventDefault(); // needed so that the drop event fires (https://stackoverflow.com/questions/21339924/drop-event-not-firing-in-chrome)
 
 			if (this.callbacks.onDragOver) {
-				this.callbacks.onDragOver(e);
+				this.callbacks.onDragOver(e, e.timeStamp - this.dragStartTime);
 			}
 		}));
 
@@ -1739,17 +1742,23 @@ export class DragAndDropObserver extends Disposable {
 			this.counter--;
 
 			if (this.counter === 0) {
+				this.dragStartTime = 0;
+
 				this.callbacks.onDragLeave(e);
 			}
 		}));
 
 		this._register(addDisposableListener(this.element, EventType.DRAG_END, (e: DragEvent) => {
 			this.counter = 0;
+			this.dragStartTime = 0;
+
 			this.callbacks.onDragEnd(e);
 		}));
 
 		this._register(addDisposableListener(this.element, EventType.DROP, (e: DragEvent) => {
 			this.counter = 0;
+			this.dragStartTime = 0;
+
 			this.callbacks.onDrop(e);
 		}));
 	}

src/vs/workbench/browser/parts/editor/tabsTitleControl.ts

@@ -97,6 +97,8 @@ export class TabsTitleControl extends TitleControl {
 
 	private static readonly TAB_HEIGHT = 35;
 
+	private static readonly DRAG_OVER_OPEN_TAB_THRESHOLD = 1500;
+
 	private static readonly MOUSE_WHEEL_EVENT_THRESHOLD = 150;
 	private static readonly MOUSE_WHEEL_DISTANCE_THRESHOLD = 1.5;
 
@@ -898,6 +900,15 @@ export class TabsTitleControl extends TitleControl {
 				this.updateDropFeedback(tab, true, index);
 			},
 
+			onDragOver: (_, dragDuration) => {
+				if (dragDuration >= TabsTitleControl.DRAG_OVER_OPEN_TAB_THRESHOLD) {
+					const draggedOverTab = this.group.getEditorByIndex(index);
+					if (draggedOverTab && this.group.activeEditor !== draggedOverTab) {
+						this.group.openEditor(draggedOverTab, { preserveFocus: true });
+					}
+				}
+			},
+
 			onDragLeave: () => {
 				tab.classList.remove('dragged-over');
 				this.updateDropFeedback(tab, false, index);