src/vs/editor/contrib/colorPicker/browser/colorPickerWidget.ts/SaturationBox/onPointerDown
class SaturationBox:	private onPointerDown(e: PointerEvent): void {
		if (!e.target || !(e.target instanceof Element)) {
			return;
		}
		this.monitor = this._register(new GlobalPointerMoveMonitor());
		const origin = dom.getDomNodePagePosition(this.domNode);

		if (e.target !== this.selection) {
			this.onDidChangePosition(e.offsetX, e.offsetY);
		}

		this.monitor.startMonitoring(e.target, e.pointerId, e.buttons, event => this.onDidChangePosition(event.pageX - origin.left, event.pageY - origin.top), () => null);

		const pointerUpListener = dom.addDisposableListener(document, dom.EventType.POINTER_UP, () => {
			this._onColorFlushed.fire();
			pointerUpListener.dispose();
			if (this.monitor) {
				this.monitor.stopMonitoring(true);
				this.monitor = null;
			}
		}, true);
	}