### 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 < plugins_list.size(); i++) {
		plugins_list[i]->forward_3d_draw_over_viewport(p_overlay);
	}
}
void EditorPluginList::forward_3d_force_draw_over_viewport(Control *p_overlay) {
	for (int i = 0; i < plugins_list.size(); i++) {
		plugins_list[i]->forward_3d_force_draw_over_viewport(p_overlay);
	}
}
void EditorPluginList::add_plugin(EditorPlugin *p_plugin) {
	ERR_FAIL_COND(plugins_list.has(p_plugin));
	plugins_list.push_back(p_plugin);
}
void EditorPluginList::remove_plugin(EditorPlugin *p_plugin) {
	plugins_list.erase(p_plugin);
}
bool EditorPluginList::is_empty() {
	return plugins_list.is_empty();
}
void EditorPluginList::clear() {
	plugins_list.clear();
}
EditorPluginList::EditorPluginList() {
}
EditorPluginList::~EditorPluginList() {
}