src/vs/editor/contrib/colorPicker/colorPickerWidget.ts/Strip/onMouseDown
class Strip:	private onMouseDown(e: MouseEvent): void {
		const monitor = this._register(new GlobalMouseMoveMonitor<IStandardMouseMoveEventData>());
		const origin = dom.getDomNodePagePosition(this.domNode);
		this.domNode.classList.add('grabbing');

		if (e.target !== this.slider) {
			this.onDidChangeTop(e.offsetY);
		}

		monitor.startMonitoring(<HTMLElement>e.target, e.buttons, standardMouseMoveMerger, event => this.onDidChangeTop(event.posy - origin.top), () => null);

		const mouseUpListener = dom.addDisposableGenericMouseUpListner(document, () => {
			this._onColorFlushed.fire();
			mouseUpListener.dispose();
			monitor.stopMonitoring(true);
			this.domNode.classList.remove('grabbing');
		}, true);
	}