src/vs/workbench/contrib/files/browser/views/explorerView.ts/ExplorerView/updateCompressedNavigationContextKeys
class ExplorerView:	private updateCompressedNavigationContextKeys(controller: ICompressedNavigationController): void {
		this.compressedFocusFirstContext.set(controller.index === 0);
		this.compressedFocusLastContext.set(controller.index === controller.count - 1);
	}