This extension to Plasma makes a menu entry on any application context menu (right click title bar) which allows locking/unlocking the window's geometry (width/height/x/y).
curl -q -L --output kwin-lock-window-placement-master.zip https://github.com/Tatsh/kwin-lock-window-placement/archive/master.zip && plasmapkg2 --install kwin-lock-window-placement-master.zip
Same as above but with --upgrade
:
curl -q -L --output kwin-lock-window-placement-master.zip https://github.com/Tatsh/kwin-lock-window-placement/archive/master.zip && plasmapkg2 --upgrade kwin-lock-window-placement-master.zip
plasmapkg2 --type KWin/Script --remove lockWindowPlacement