I just made a jump from Maté to KDE Plasma. (Kubuntu v. 14.04.4) (I love everything else about it.) I'm hardly a linux beginner, but I don't usually mess with X and some help is appreciated.
When I first start my machine, everything runs smoothly, but standard keyboard shortcuts (like ALT+TAB and CTRL+ALT+RIGHT) are not recognized. Every window does accept keyboard input; just not the window manager.
For the moment, I can fix this by switching from KWin to Compiz, and then back; after that, everything works fine and I can get on with my work. However, it's something I would like to find a permanent solution to, if I can.
Thanks for any tips and pointers anyone has to offer on this.
Figured it out.
I was using Maté before; and Compiz was my preferred window manager. So, I had it set up to run "compiz --replace" on startup. KDE doesn't need it, of course; and when it ran, it hijacked keyboard shortcuts.
Now that I've disabled it, everything's running smoothly.