### 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
for (int i = 0; i < editor_data.get_edited_scene_count(); i++) {
		Node *node = editor_data.get_edited_scene_root(i);
		if (!node) {
			continue;
		}
		String path = node->get_scene_file_path();
		if (!path.is_empty() && !FileAccess::exists(path)) {
			
			EditorUndoRedoManager::get_singleton()->set_history_as_unsaved(editor_data.get_scene_history_id(i));
		}
	}
	_update_title();
	_update_scene_tabs();
}
void EditorNode::_dialog_action(String p_file) {