src/vs/workbench/services/dialogs/browser/simpleFileDialog.ts/SimpleFileDialog/root
class SimpleFileDialog:	private root(value: URI) {
		let lastDir = value;
		let dir = resources.dirname(value);
		while (!resources.isEqual(lastDir, dir)) {
			lastDir = dir;
			dir = resources.dirname(dir);
		}
		return dir;
	}