git clone https://github.com/insidewhy/kwin-window-switch
cd kwin-window-switch
# if on plasma5 run this:
# git checkout plasma5
make installThe default KDE window switcher involves a "tab box" mode which blocks all further key bindings until the modifier key is removed. This script switches windows immediately without blocking key bindings.
After installing this script the keybindings can be customised in the "global shortcuts" settings under the KWin component via Select next window and Select previous window.
This was original written in QML where two of the needed APIs weren't available. The fixes to these are now in KDE, the relevant bugs can be found below: