This morning I got all the application on my Ubuntu 12.04 missed the close/minimize/maximize button. For example this linux terminal.I has CompizConfig Setting Manager (Application -> System Tools -> Preferences -> CompizConfig Setting Manager) that arranged that kind of task but it seemed dont work that time. Someone said to CHECK the ‘Window Decoration’ menu inEffect Section. Its already checked! I tried to uncheck the menu and check it back and IT WORK.