bug#19482: Changing to big font cause display problem

[martin rudalics]

> That's the fact. Emacs doesn't know the real size of frame and is using a 
> wrong frame size.
> This must be the cause of the display problem.

So it seems that we have located the bug now.

>> Indeed.  The problem is to find out what the limits are.

First we have to find out whether and how your window manager does tell
us the limits and/or why Emacs apparently ignores them.

> I will try the Emacs 25.

Fine.  I'll tell you what to do when you're ready.

martin