Originally Posted by raffaele181188
Slackware current, Qt 4.4.3
We are not on the "cutting edge" :-D So I think this is not a Qt issue...
In fact the problem with the border was a known Qt problem I faced as well. Plasma used a workaround which didn't work anymore in Qt 4.5rc, and which is not needed anymore in 4.5 final. Since kde 4.2.1 got some updates related to Qt this might be your problem.
First please try to see whether the problem occurs with a non-nvidia driver as well. If it doesn't: probably really a Qt problem.
Else: please provide a nvidia bug report.
With the new driver and KDE 4.2.1 built against Qt 4.5 I am currently not facing this issue.