### 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
return EditorNode::get_singleton()->get_edited_scene();
}
void EditorNode::_print_handler(void *p_this, const String &p_string, bool p_error, bool p_rich) {
	callable_mp_static(&EditorNode::_print_handler_impl).bind(p_string, p_error, p_rich).call_deferred();
}
void EditorNode::_print_handler_impl(const String &p_string, bool p_error, bool p_rich) {
	if (p_error) {
		singleton->log->add_message(p_string, EditorLog::MSG_TYPE_ERROR);
	} else if (p_rich) {
		singleton->log->add_message(p_string, EditorLog::MSG_TYPE_STD_RICH);
	} else {
		singleton->log->add_message(p_string, EditorLog::MSG_TYPE_STD);
	}
}
static void _execute_thread(void *p_ud) {