Wow, it's strange that you can't reproduce! Glad you could siebe... I'm not crazy after all.
@Joonas: are you using 5.22?
Also, great idea with the right click and drag. It works quite well.. Although the first time, I tried to right click and drag without selecting first... Which didn't work, obviously. Try the following:
1) Select an item in the playlist
2) right click on a different item and drag... without selecting it first..
As expected, the selected item is the one that gets dragged, not the one that was right clicked on. This isn't a problem, but it's different than typical implementations of right click and drags (like Windows Explorer type). Probably nothing you can do about it.. Just a small usability concern