src/vs/workbench/browser/parts/editor/editorGroupView.ts/EditorGroupView/onShowContainerContextMenu
class EditorGroupView:	private onShowContainerContextMenu(menu: IMenu, e?: MouseEvent): void {
		if (!this.isEmpty) {
			return; // only for empty editor groups
		}

		// Find target anchor
		let anchor: HTMLElement | { x: number, y: number } = this.element;
		if (e instanceof MouseEvent) {
			const event = new StandardMouseEvent(e);
			anchor = { x: event.posx, y: event.posy };
		}

		// Fill in contributed actions
		const actions: IAction[] = [];
		const actionsDisposable = createAndFillInContextMenuActions(menu, undefined, actions);

		// Show it
		this.contextMenuService.showContextMenu({
			getAnchor: () => anchor,
			getActions: () => actions,
			onHide: () => {
				this.focus();
				dispose(actionsDisposable);
			}
		});
	}