Finally got around to uninstalling with Revo (which I love) and cleaning the Registry before re-installing. No joy. But I did notice it usually happens after the screensaver has been active.

Version 28.0.1750.51 on Windows 8, 64

After I click on menu the outline is left on the screen. https://www.dropbox.com/s/xu9or4vcmfblu16/opera.png?dl=0

It stays if I minimize and restore, open a new window or tab or switch Opera to a different monitor. This happens in no other application. If I close Opera and open it; it is gone, but it returns the first time I click on the menu.