### Godot version

v4.2.dev.custom_build [0c2144da9]

### System information

Debian Linux X11 Xfce

### Issue description

Prerequisite: Be in Single Window Mode in the Editor
The Filesystem Dock is unusable when it is floating, which is not expected.
It appears garbled in the top-left corner:
![image](https://github.com/godotengine/godot/assets/6299227/109f7922-97de-44c3-814a-ca7f970e0602)

The following errors are shown:
```
  editor/window_wrapper.cpp:220 - Condition "!is_window_available()" is true.
  editor/window_wrapper.cpp:202 - Condition "!get_window_enabled()" is true. Returning: Rect2i()
  editor/window_wrapper.cpp:207 - Condition "!get_window_enabled()" is true. Returning: -1
  editor/window_wrapper.cpp:207 - Condition "!get_window_enabled()" is true. Returning: -1
```

bisecting lead to #62378
possibly related to #44439

### Steps to reproduce

1. Start a project in the Editor
2. Switch to Single Window Mode in the Editor and reload (if necessary)
3. Make the Filesystem Dock floating

### Minimal reproduction project

Editor issue
while (!eta.done.is_set()) {
		{
			MutexLock lock(eta.execute_output_mutex);
			if (prev_len != eta.output.length()) {
				String to_add = eta.output.substr(prev_len, eta.output.length());
				prev_len = eta.output.length();
				execute_outputs->add_text(to_add);
				DisplayServer::get_singleton()->process_events(); 
				Main::iteration();
			}
		}
		OS::get_singleton()->delay_usec(1000);
	}
	eta.execute_output_thread.wait_to_finish();
	execute_outputs->add_text("\nExit Code: " + itos(eta.exitcode));
	if (execute_output_dialog) {
		if (p_close_on_errors && eta.exitcode != 0) {
			execute_output_dialog->hide();
		}
		if (p_close_on_ok && eta.exitcode == 0) {
			execute_output_dialog->hide();
		}
		execute_output_dialog->get_ok_button()->set_disabled(false);
	}
	return eta.exitcode;
}
void EditorNode::notify_settings_changed() {
	settings_changed = true;
}
EditorNode::EditorNode() {