use some closure data to avoid blocking click-on-selection

src/vs/editor/browser/controller/mouseHandler.ts

@@ -348,6 +348,7 @@ class MouseDownOperation extends Disposable {
 	private _mouseDragThenMoveEventHandler: EventGateKeeper<EditorMouseEvent>;
 
 	private _currentSelection: Selection;
+	private _dragTargetPosition: Position;
 	private _mouseState: MouseDownState;
 
 	private _onScrollTimeout: TimeoutTimer;
@@ -410,6 +411,7 @@ class MouseDownOperation extends Disposable {
 			return;
 		}
 
+
 		this._dispatchMouse(position, MouseDownEventType.Select);
 	}
 
@@ -423,6 +425,7 @@ class MouseDownOperation extends Disposable {
 			return;
 		}
 
+		this._dragTargetPosition = position.position;
 		this._dispatchMouse(position, MouseDownEventType.Drag);
 	}
 
@@ -449,12 +452,13 @@ class MouseDownOperation extends Disposable {
 			&& this._currentSelection.containsPosition(position.position) // single click on a selection
 		) {
 			this._isActive = true;
+			this._dragTargetPosition = position.position;
 
 			this._mouseMoveMonitor.startMonitoring(
 				createMouseMoveEventMerger(null),
 				this._mouseDragThenMoveEventHandler.handler,
 				() => {
-					this._viewController.dragTo('mouse', position.position);
+					this._viewController.dragTo('mouse', this._dragTargetPosition);
 					this._stop();
 				}
 			);

src/vs/editor/common/controller/cursor.ts

@@ -1357,12 +1357,19 @@ export class Cursor extends EventEmitter {
 			return false;
 		}
 
-		var lastAddedCursor = this.cursors.getLastAddedCursor();
+		let dragTargetPosition = ctx.eventData.position;
+		if (selections[0].containsPosition(dragTargetPosition)) {
+			this._invokeForAll(ctx, (cursorIndex: number, oneCursor: OneCursor, oneCtx: IOneCursorOperationContext) => {
+				if (oneCursor.modelState.selection.containsPosition(dragTargetPosition)) {
+					return OneCursorOp.moveTo(oneCursor, false, ctx.eventData.position, ctx.eventData.viewPosition, ctx.eventSource, oneCtx);
+				}
+				return false;
+			});
 
-		if (selections[0].containsPosition(lastAddedCursor.modelState.position)) {
-			return false;
+			return true;
 		}
 
+		var lastAddedCursor = this.cursors.getLastAddedCursor();
 		this._invokeForAll(ctx, (cursorIndex: number, oneCursor: OneCursor, oneCtx: IOneCursorOperationContext) => {
 			if (oneCursor !== lastAddedCursor) {
 				return this._doApplyEdit(cursorIndex, oneCursor, oneCtx, () => new EditOperationResult(new DragAndDropCommand(oneCursor.modelState.selection, lastAddedCursor.modelState.position), {