Ok. I suppose it is related to https://bugreports.qt.io/browse/QTBUG-56610, which is an nvidia specific issue. From https://devtalk.nvidia.com/default/topic/971972/linux/icon-text-label-corruption-with-kde-plasma-5-desktop-folder-view/ (being referred to in that Qt bug report): This is probably the result of a quirk of the way the nvidia driver manages memory for "volatile" data like framebuffer objects. The contents of FBOs are not preserved across VT switches, which includes suspend and resume. Recent drivers support an extension called GL_NV_robustness_video_memory_purge that applications can use to be notified when they need to re-render FBO contents. A patch to support this nvidia extension has been merged into qtbase a few days ago (will be in 5.11), but apparently there's still some work needed.