### 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
EditorNode::ExecuteThreadArgs *eta = (EditorNode::ExecuteThreadArgs *)p_ud;
	Error err = OS::get_singleton()->execute(eta->path, eta->args, &eta->output, &eta->exitcode, true, &eta->execute_output_mutex);
	print_verbose("Thread exit status: " + itos(eta->exitcode));
	if (err != OK) {
		eta->exitcode = err;
	}
	eta->done.set();
}
int EditorNode::execute_and_show_output(const String &p_title, const String &p_path, const List<String> &p_arguments, bool p_close_on_ok, bool p_close_on_errors) {
	if (execute_output_dialog) {
		execute_output_dialog->set_title(p_title);
		execute_output_dialog->get_ok_button()->set_disabled(true);
		execute_outputs->clear();
		execute_outputs->set_scroll_follow(true);
		EditorInterface::get_singleton()->popup_dialog_centered_ratio(execute_output_dialog);
	}
	ExecuteThreadArgs eta;
	eta.path = p_path;
	eta.args = p_arguments;
	eta.exitcode = 255;
	int prev_len = 0;
	eta.execute_output_thread.start(_execute_thread, &eta);