### 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
if (p_res.is_null()) {
		return false;
	}
	if (processed.has(p_res)) {
		return processed[p_res];
	}
	bool changed = p_res->is_edited();
	p_res->set_edited(false);
	bool subchanged = _find_and_save_edited_subresources(p_res.ptr(), processed, flags);
	if (p_res->get_path().is_resource_file()) {
		if (changed || subchanged) {
			ResourceSaver::save(p_res, p_res->get_path(), flags);
		}
		processed[p_res] = false; 
		return false;
	} else {
		processed[p_res] = changed;
		return changed;
	}
}
bool EditorNode::_find_and_save_edited_subresources(Object *obj, HashMap<Ref<Resource>, bool> &processed, int32_t flags) {