Not sure if that's a bug or if it's the fault of kdenlive at all...

But I've been really annoyed by a 'feature' of manipulating sliders with the scroll wheel:
If your mouse pointer is above such a slider, the mouse wheel will change the slider. That's great. But if the slider hits a limit, suddenly the scroll request is relayed to the next canvas. If that one is too small to fit and has scrollbars, you start scrolling it, at least until your mouse cursor hits another 'scrollable' element. In that case the scroll request is again directed to the new element, and it gets changed.

I don't know how many settings I had to revert because of this :-(
So if there's something you can do about it...
(this is 0.8.2.1 on an openSUSE 11.4 with KDE SC 4.6)