bug#24746: parts of buffer become invisible

[Eli Zaretskii <eliz@gnu.org>]

> Date: Thu, 20 Oct 2016 16:57:34 +0000 (UTC)
> From: Bob Krovetz <bkrovetz@yahoo.com>
> 
> I am using emacs 24.5.1 on Ubuntu 16.04. Sometimes parts of the buffer become invisible. For example, in
> the minibuffer the part that represents the command and partial argument can become invisible, such as c-x
> c-f failing to show "Find file: " and the directory string. In Perl I have found parts of the buffer that highlight
> different components such as variable names or programming language words might also become invisible,
> so the problem is not just about the minibuffer. The problem does not go away when using 'emacs -Q'. I used
> to use an older version of Ubuntu that is no longer supported, and the problem started appearing after I
> upgraded to 16.04.
> 
> Can you help me understand what is happening, and what I might do to debug it? I started looking at overlays
> and text properties, but I still don't understand them well enough. The characters can be seen when I
> backspace over them. I cannot predict when the problem will occur, and the current remedy is to exit emacs
> and start again.

Look at the settings of your video driver.  If there's some kind of
"optimization" features there, turn them off and see if that helps.