### 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
load_scene(p_resource->get_path().get_slice("::", 0));
	InspectorDock::get_singleton()->call_deferred("edit_resource", p_resource);
}
bool EditorNode::is_resource_read_only(Ref<Resource> p_resource, bool p_foreign_resources_are_writable) {
	ERR_FAIL_COND_V(p_resource.is_null(), false);
	String path = p_resource->get_path();
	if (!path.is_resource_file()) {
		
		int srpos = path.find("::");
		if (srpos != -1) {
			String base = path.substr(0, srpos);
			
			if (ResourceLoader::get_resource_type(base) == "PackedScene") {
				if (!get_tree()->get_edited_scene_root() || get_tree()->get_edited_scene_root()->get_scene_file_path() != base) {
					
					
					if (!p_foreign_resources_are_writable || FileAccess::exists(base + ".import")) {
						return true;
					}
				}
			} else {
				
				if (FileAccess::exists(base + ".import")) {