This has happened since 11.10 if my memory is correct. If I minimize this application there seem to be no way that I know to get it back. Is this a unity bug or compiz bug? There is no triangle on both sides of the application, different from this question: Sometimes applications stay in the background and have an empty white arrow in the launcher. How do I fix this?
gimp is running but I do not know how to bring it to the front.