src/vs/editor/browser/editorDom.ts/GlobalEditorPointerMoveMonitor/startMonitoring
class GlobalEditorPointerMoveMonitor:	public startMonitoring(
		initialElement: Element,
		pointerId: number,
		initialButtons: number,
		pointerMoveCallback: (e: EditorMouseEvent) => void,
		onStopCallback: (browserEvent?: PointerEvent | KeyboardEvent) => void
	): void {

		// Add a <<capture>> keydown event listener that will cancel the monitoring
		// if something other than a modifier key is pressed
		this._keydownListener = dom.addStandardDisposableListener(<any>document, 'keydown', (e) => {
			const kb = e.toKeybinding();
			if (kb.isModifierKey()) {
				// Allow modifier keys
				return;
			}
			this._globalPointerMoveMonitor.stopMonitoring(true, e.browserEvent);
		}, true);

		this._globalPointerMoveMonitor.startMonitoring(
			initialElement,
			pointerId,
			initialButtons,
			(e) => {
				pointerMoveCallback(new EditorMouseEvent(e, true, this._editorViewDomNode));
			},
			(e) => {
				this._keydownListener!.dispose();
				onStopCallback(e);
			}
		);
	}