### 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
String current_renderer = GLOBAL_GET("rendering/renderer/rendering_method");
	PackedStringArray renderers = ProjectSettings::get_singleton()->get_custom_property_info().get(StringName("rendering/renderer/rendering_method")).hint_string.split(",", false);
	
	
	current_renderer = current_renderer.to_lower();
	for (int i = 0; i < renderers.size(); i++) {
		String rendering_method = renderers[i];
		
		if (rendering_method == "forward_plus") {
			renderer->add_item(TTR("Forward+"));
		}
		if (rendering_method == "mobile") {
			renderer->add_item(TTR("Mobile"));
		}
		if (rendering_method == "gl_compatibility") {
			renderer->add_item(TTR("Compatibility"));
		}
		renderer->set_item_metadata(i, rendering_method);
		
		rendering_method = rendering_method.to_lower();
		if (current_renderer == rendering_method) {
			renderer->select(i);
			renderer_current = i;
		}
	}
	_update_renderer_color();
	video_restart_dialog = memnew(ConfirmationDialog);
	video_restart_dialog->set_text(TTR("Changing the renderer requires restarting the editor."));
	video_restart_dialog->set_ok_button_text(TTR("Save & Restart"));
	video_restart_dialog->connect("confirmed", callable_mp(this, &EditorNode::_menu_option).bind(SET_RENDERER_NAME_SAVE_AND_RESTART));