If you don't find what you need here, check out #beholderveekubuntuguides , there might be the thing you're looking for.
A fresh install of Kubuntu has this annoying behavior: when you click, hold and drag an empty space in a window, it will move the window. This might be ok if you use a mouse, but if you use a touchscreen this will be a nightmare.
Without any further ado, here's the solution:
Press Alt+Space. In the text field that has appeared type in 'Widget Style' and choose the first option from the drop-down. In the General tab find 'Windows' drag mode' and choose 'Drag windows from titlebar only'. Don't forget to click 'apply'.
That's it.