Very annoying problem

[René J.V. Bertin]

On Wednesday March 27 2019 11:10:55 Leon Pollak wrote:

>To be more precise - when the screen switches everything looks OK for the 
>first second, may be two. Then something springs out and this screen part 
>displays the previous fragment.
>If I switch to another application (mc in example) and return - this part of 
>mc screen remains.

I think the symptoms are not directly related to KDevelop. I see something like what you describe from time to time when I switch desktops and am using a simpler window manager than KWin (xfwm4). Parts of the display are not being updated and this has to do somehow with the compositor (= the component responsible for more fancy GUI things; effects, transparency etc).

Of course the window manager (and thus the compositor) is independent from KDevelop and should not be affected by what you're doing in KDevelop. The only things I can think of that could explain (supposing you're using X11 and not Wayland of which I know nothing!):

- you're trying to debug the window manager. That'd be a very bad idea so I'm pretty certain you're not doing that
- your application does fancy (OpenGL) things itself, or you have a lot of UI effects configured, and you interrupt the application in the middle of doing such things. A bit like when you trigger a breakpoint in a location that does something with a popup or modal dialog which is already open; you're stuck because the application had grabbed mouse and keyboard so you cannot control the debugger and the application is paused.

If you are using KWin (= you run a standard KDE Plasma desktop environment) then you can turn off the compositor and UI effects via the systemsettings. There's also a hotkey for toggling it. You could try that, preferably before you start debugging.

R.