I've had this problem both on KDE on Debian 9, as well as my current setup which is KDE neon 5.12, plasma version 5.12.4.

It usually happens with firefox, but it's also happened with the terminator terminal program. This only happens to a single window though, I have usually 5 or 6 firefox or terminator windows open and it only happens to one at a time, but it's permanent on that window. The application will stop repainting, for example, when I click on different tabs in Firefox. However, the title bar updates with the name of the newly selected tab. If I grab the titlebar and move the window, it updates as long as it is moving. If I move the tas to a new firefox window, the new window behaves normally and I can get to the tabs again. So far I've had it with those 2 applications, however I think I may have seen it with other apps on my past KDE systems in the last year or so.

I am using a binary nvidia driver, if that helps.

Any ideas? Since I've had this on multiple installs I imagine someone else must have had the same kind of experience.

Yep, same. I'm using an nvidia binary driver for my GTX 1060, KDE Plasma on Ubuntu 20.04. My application that stops painting is Chrome. It seems to happen after the app has been sitting a while, may be related to video / graphics intensive processing. (e.g. once it sat overnight on page using the webcam.)

A couple workarounds:
- If it's just one window, I can sometimes CTRL-N to create a new browser window, and move the tabs over (copy-paste the URLs)
- Failing all else, I can click, resize the window to force a repaint, click, resize the window...

I'd appreciate any other fix / workaround info.

I have same problems on 2 kde machines (kubuntu, kde neon). Happens mostly with firefox and intellij idea.

I found that executing these commands resolves this issue:

Code: Select all

killall kwin_x11
kwin_x11 --replace