Zig zag side edges when I move a window around quickly

[René J.V. Bertin]

On Wednesday March 15 2017 06:13:22 Duncan wrote:

>That's easily togglable (and strength configurable when it's on) as kwin's 
>wobbly-windows effect.  Plasma system settings, Workspace, Desktop 
>Behavior, Desktop Effects.  There's a big list broken into categories.  
>In the Appearance category, uncheck or hit the reconfigure icon for 
>Wobbly Windows, and you can turn it off entirely (uncheck) or reduce/
>increase the wobbliness (configure).

That's presuming the OP has the effect enabled in the first place. What he describes can also be the result of a particularly bad video configuration where the software draws much faster than the hardware can follow.
First things to check are if you're using the best drawing method the hardware can support; XRender/Native for anything that doesn't support OpenGL properly, OpenGL/Raster for hardware that does. That's probably in the compositor settings with Plasma5. Then you have to experiment with tearing prevention. I never tried to figure out the exact meaning of the different options but basically it means you start a screen content update when the monitor is about to start its own refresh (on old CRTs that would be when the electron beam was about to go back to the top-left screen corner).
If your screen has a refresh rate of 50ms or better (20 frames/sec or more) you shouldn't notice any issues with moving, resizing etc (fast and/or very fine-grained animations may suffer but those are candy anyway).

If you like to see window geometry displayed when moving windows, use the desktop effect and not the option in the KWin/Moving settings (and certainly not both).

Finally, glitches like the OP describes can probably be attenuated by making window contents transparent while moving. That's a desktop option that also works with the XRender backend, and a very useful one (an almost perfect marriage between moving the window frame only as I usually prefer, and solid/opaque moves).

R.