src/vs/base/browser/ui/scrollbar/abstractScrollbar.ts/AbstractScrollbar/delegateMouseDown
class AbstractScrollbar:	public delegateMouseDown(e: IMouseEvent): 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 mousePos = this._sliderMousePosition(e);
		if (sliderStart <= mousePos && mousePos <= sliderStop) {
			// Act as if it was a mouse down on the slider
			if (e.leftButton) {
				e.preventDefault();
				this._sliderMouseDown(e, () => { /*nothing to do*/ });
			}
		} else {
			// Act as if it was a mouse down on the scrollbar
			this._onMouseDown(e);
		}
	}