Periodically menus in Qt Creator will disappear. I've attached a video show this in action. I don't know what causes it yet, it just happens after a certain amount of usage. So far the only fix I've found is to quit Qt Creator and relaunch.

At the 0:01 mark, I click the Project icon in the lower left corner, and the popup menu is not seen. Around the 0:06 mark I click the File menu, again no menu is visible. While that menu was clicked, I move the mouse to the right (without any further clicks) over the other menus, none of them show either. Then around the 0:14 mark, I click just below the File menu and you can see the New File or Project dialog appears. So the menus are present and work, they just aren't visible

I did not have this problem with Qt Creator 4.3.0