setDocumentEdited static method
Sets the document to be edited.
This changes the appearance of the close button on the titlebar:
![image](https://user-images.githubusercontent.com/86920182/209436903-0a6c1f5a-4ab6-454f-a37d-78a5d699f3df.png)
Implementation
static Future<void> setDocumentEdited() async {
await _completer.future;
await _windowManipulatorMethodChannel.invokeMethod('setDocumentEdited');
}