### 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
}
	editor_selection->clear();
	editor_data.set_edited_scene(p_idx);
	Node *new_scene = editor_data.get_edited_scene_root();
	if (Popup *p = Object::cast_to<Popup>(new_scene)) {
		p->show();
	}
	SceneTreeDock::get_singleton()->set_edited_scene(new_scene);
	if (get_tree()) {
		get_tree()->set_edited_scene_root(new_scene);
	}
	if (new_scene) {
		if (new_scene->get_parent() != scene_root) {
			scene_root->add_child(new_scene, true);
		}
	}
	Dictionary state = editor_data.restore_edited_scene_state(editor_selection, &editor_history);
	_edit_current(true);
	_update_title();
	_update_scene_tabs();
	call_deferred(SNAME("_set_main_scene_state"), state, get_edited_scene()); 
}
void EditorNode::setup_color_picker(ColorPicker *p_picker) {
	p_picker->set_editor_settings(EditorSettings::get_singleton());
	int default_color_mode = EDITOR_GET("interface/inspector/default_color_picker_mode");
	int picker_shape = EDITOR_GET("interface/inspector/default_color_picker_shape");
	p_picker->set_color_mode((ColorPicker::ColorModeType)default_color_mode);
	p_picker->set_picker_shape((ColorPicker::PickerShapeType)picker_shape);
}
bool EditorNode::is_scene_open(const String &p_path) {