src/vs/workbench/browser/parts/compositeBar.ts/CompositeBar/insertAtFront
class CompositeBar:	private insertAtFront(element: HTMLElement, event: DragEvent): boolean {
		const rect = element.getBoundingClientRect();
		const posX = event.clientX;
		const posY = event.clientY;

		switch (this.options.orientation) {
			case ActionsOrientation.HORIZONTAL:
				return posX < rect.left;
			case ActionsOrientation.VERTICAL:
				return posY < rect.top;
		}
	}