### 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
resource_conversion_plugins.push_back(p_plugin);
}
void EditorNode::remove_resource_conversion_plugin(const Ref<EditorResourceConversionPlugin> &p_plugin) {
	resource_conversion_plugins.erase(p_plugin);
}
Vector<Ref<EditorResourceConversionPlugin>> EditorNode::find_resource_conversion_plugin(const Ref<Resource> &p_for_resource) {
	Vector<Ref<EditorResourceConversionPlugin>> ret;
	for (int i = 0; i < resource_conversion_plugins.size(); i++) {
		if (resource_conversion_plugins[i].is_valid() && resource_conversion_plugins[i]->handles(p_for_resource)) {
			ret.push_back(resource_conversion_plugins[i]);
		}
	}
	return ret;
}
void EditorNode::_bottom_panel_raise_toggled(bool p_pressed) {
	top_split->set_visible(!p_pressed);
}
void EditorNode::_update_renderer_color() {
	String rendering_method = renderer->get_selected_metadata();
	if (rendering_method == "forward_plus") {
		renderer->add_theme_color_override("font_color", Color::hex(0x5d8c3fff));
	}
	if (rendering_method == "mobile") {
		renderer->add_theme_color_override("font_color", Color::hex(0xa5557dff));
	}
	if (rendering_method == "gl_compatibility") {
		renderer->add_theme_color_override("font_color", Color::hex(0x5586a4ff));
	}
}
void EditorNode::_renderer_selected(int p_which) {