Well, try to think a plasmoid which is not clickable but only appear with transparency upon all the windows where you are working on, it will be very useful to work at full screen with a calc window, and having the clock at the center of the screen and a superkaramba theme and the battery monitor which transparently cover your work but do not prevent to write through the plasmoids on the calc window. what do you say about??
Sounds too niche. You can recreate an effect using plasmawindowed and kwin's window rules.
...plasmawindowed?? what is it? how can I use?