### 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 changing_scene;
}
void EditorNode::set_current_scene(int p_idx) {
	
	if (editor_data.get_scene_path(p_idx) != "" && editor_data.get_edited_scene_root(p_idx)) {
		editor_folding.save_scene_folding(editor_data.get_edited_scene_root(p_idx), editor_data.get_scene_path(p_idx));
	}
	if (editor_data.check_and_update_scene(p_idx)) {
		if (editor_data.get_scene_path(p_idx) != "") {
			editor_folding.load_scene_folding(editor_data.get_edited_scene_root(p_idx), editor_data.get_scene_path(p_idx));
		}
		EditorUndoRedoManager::get_singleton()->clear_history(false, editor_data.get_scene_history_id(p_idx));
	}
	changing_scene = true;
	editor_data.save_edited_scene_state(editor_selection, &editor_history, _get_main_scene_state());
	if (get_editor_data().get_edited_scene_root()) {
		if (get_editor_data().get_edited_scene_root()->get_parent() == scene_root) {
			scene_root->remove_child(get_editor_data().get_edited_scene_root());
		}