src/vs/workbench/browser/parts/sidebar/sidebarPart.ts/SidebarPart/onTitleAreaContextMenu
class SidebarPart:	private onTitleAreaContextMenu(event: StandardMouseEvent): void {
		const activeViewlet = this.getActivePaneComposite() as PaneComposite;
		if (activeViewlet) {
			const contextMenuActions = activeViewlet ? activeViewlet.getContextMenuActions() : [];
			if (contextMenuActions.length) {
				const anchor: { x: number; y: number } = { x: event.posx, y: event.posy };
				this.contextMenuService.showContextMenu({
					getAnchor: () => anchor,
					getActions: () => contextMenuActions.slice(),
					getActionViewItem: action => this.actionViewItemProvider(action),
					actionRunner: activeViewlet.getActionRunner()
				});
			}
		}
	}