### 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
docks_visible = p_show;
	_update_dock_slots_visibility(true);
}
bool EditorNode::get_docks_visible() const {
	return docks_visible;
}
void EditorNode::_toggle_distraction_free_mode() {
	if (EDITOR_GET("interface/editor/separate_distraction_mode")) {
		int screen = -1;
		for (int i = 0; i < editor_table.size(); i++) {
			if (editor_plugin_screen == editor_table[i]) {
				screen = i;
				break;
			}
		}
		if (screen == EDITOR_SCRIPT) {
			script_distraction_free = !script_distraction_free;
			set_distraction_free_mode(script_distraction_free);
		} else {
			scene_distraction_free = !scene_distraction_free;
			set_distraction_free_mode(scene_distraction_free);
		}
	} else {
		set_distraction_free_mode(distraction_free->is_pressed());
	}
}
void EditorNode::set_distraction_free_mode(bool p_enter) {