That is because GParted is running as root and as such has no access to the service that shows menus outside the application. The same happens when you run other GUI applications as root or as another user than the desktop user (e.g. Synaptic).
That is because GParted is running as root and as such has no access to the service that shows menus outside the application. The same happens when you run other GUI applications as root or as another user than the desktop user (e.g. Synaptic).