### 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
center_split->set_split_offset(old_split_ofs);
}
void EditorNode::_add_to_recent_scenes(const String &p_scene) {
	Array rc = EditorSettings::get_singleton()->get_project_metadata("recent_files", "scenes", Array());
	if (rc.has(p_scene)) {
		rc.erase(p_scene);
	}
	rc.push_front(p_scene);
	if (rc.size() > 10) {
		rc.resize(10);
	}
	EditorSettings::get_singleton()->set_project_metadata("recent_files", "scenes", rc);
	_update_recent_scenes();
}
void EditorNode::_open_recent_scene(int p_idx) {
	if (p_idx == recent_scenes->get_item_count() - 1) {
		EditorSettings::get_singleton()->set_project_metadata("recent_files", "scenes", Array());
		call_deferred(SNAME("_update_recent_scenes"));
	} else {
		Array rc = EditorSettings::get_singleton()->get_project_metadata("recent_files", "scenes", Array());
		ERR_FAIL_INDEX(p_idx, rc.size());
		if (load_scene(rc[p_idx]) != OK) {
			rc.remove_at(p_idx);
			EditorSettings::get_singleton()->set_project_metadata("recent_files", "scenes", rc);
			_update_recent_scenes();
		}
	}
}
void EditorNode::_update_recent_scenes() {