src/vs/base/browser/ui/scrollbar/abstractScrollbar.ts/AbstractScrollbar/delegatePointerDown
class AbstractScrollbar:	public delegatePointerDown(e: PointerEvent): void {
		const domTop = this.domNode.domNode.getClientRects()[0].top;
		const sliderStart = domTop + this._scrollbarState.getSliderPosition();
		const sliderStop = domTop + this._scrollbarState.getSliderPosition() + this._scrollbarState.getSliderSize();
		const pointerPos = this._sliderPointerPosition(e);
		if (sliderStart <= pointerPos && pointerPos <= sliderStop) {
			// Act as if it was a pointer down on the slider
			if (e.button === 0) {
				e.preventDefault();
				this._sliderPointerDown(e);
			}
		} else {
			// Act as if it was a pointer down on the scrollbar
			this._onPointerDown(e);
		}
	}