src/vs/workbench/browser/parts/views/viewsService.ts/ViewsService/onViewsVisibilityChanged
class ViewsService:	private onViewsVisibilityChanged(view: IView, visible: boolean): void {
		this.getOrCreateActiveViewContextKey(view).set(visible);
		this._onDidChangeViewVisibility.fire({ id: view.id, visible: visible });
	}