Hello all,

When using the laptop keys (luminosity, volume and a few others), the borders around windows regularly disappear. Typing "kwin --replace &" brings them back but it's annoying (and the user can't switch windows while it's happening).

This is on an HP laptop with an intel card (Skylake GT2, HD Graphics 520, i915 driver), of which we have several running Kubuntu, but only one has this problem. I tried looking at the problem but could not find error messages in dmesg or Xorg.0.log

I tried:
- updating the system to the latest Ubuntu
- changing the rendering backend from OpenGL 2 to Xrender
- disabled the "Present Windows" effect
- changed theme
- replaced the user's kwinrc and kwinrulesrc files with factory ones
- removed Xorg.conf
- unchecked "allow applications to disable compositing" in compositor tab

Problem still present.

The only message I managed to get when running kwin manually is:
QXcbConnection: XCB error: 3 (BadWindow), sequence: 2831, resource id: 25166573, major code: 18 (ChangeProperty), minor code: 0

Any more ideas ? Thanks.