I am on '''Ubuntu'''. As by default, there is a '''title bar''' which takes up a little extra space of the viewport, I've '''disabled''' it, which gives some more space for the content. The trouble I face is, I '''do not see buttons such as Close, Minimize / Maximize, Restore / Minimize Buttons,''' but when hovered by mouse at Right Top corner, a text balloon pops-up stating the actions present there, '''invisible'''. How to make those invisible little buttons visible there?