Comment # 1 on bug 1013550 from Tomas Jensen

Same on a HP6320nc.

The issue is descriped here: 
https://bugs.kde.org/show_bug.cgi?id=349519

Fix is to:
> to put the following/creating in e. g. /etc/X11/xorg.conf.d/20-intel.conf:
> 
>     Section "Device"
>         Identifier  "Intel Graphics"
>         Driver      "intel"
>         Option      "AccelMethod"  "uxa"
>     EndSection

I've observed same with popups in Chrome, Firefox or even Plasma when plasma
reports a crash.

X can be restarted by hitting CTRL+ALT+BACKSPACE or you could escape to a shell
with CTRL+ALT+F12 and then ALT+F1

/Tomas