src/vs/workbench/services/dialogs/browser/simpleFileDialog.ts/SimpleFileDialog/showOpenDialog
class SimpleFileDialog:	public async showOpenDialog(options: IOpenDialogOptions = {}): Promise<URI | undefined> {
		this.scheme = this.getScheme(options.availableFileSystems, options.defaultUri);
		this.userHome = await this.getUserHome();
		const newOptions = this.getOptions(options);
		if (!newOptions) {
			return Promise.resolve(undefined);
		}
		this.options = newOptions;
		return this.pickResource();
	}