src/vs/workbench/services/dialogs/browser/simpleFileDialog.ts/SimpleFileDialog/insertText
class SimpleFileDialog:	private insertText(wholeValue: string, insertText: string) {
		if (this.filePickBox.inputHasFocus()) {
			document.execCommand('insertText', false, insertText);
			if (this.filePickBox.value !== wholeValue) {
				this.filePickBox.value = wholeValue;
				this.handleValueChange(wholeValue);
			}
		} else {
			this.filePickBox.value = wholeValue;
			this.handleValueChange(wholeValue);
		}
	}