Custom Palette bug

Hi,
I'm using Musecore 0.9.6 2949M Pre Release, on kubuntu 10.04. I use deb from ppa repository.

My problem is I can't neither use custom palette nor add custom symbol. I've already seen this post :
http://musescore.org/en/node/1580#comment-8053, and I've already posted this :
http://musescore.org/en/node/5581
And I tought the problem could be resolve with the pre release, but it still doesn't work on my computer :-(

When the default symbol palette is checked as editable, is there any special keyboard combination or other stuff to do to drag the symbol from the score to the palette?? Because dragging the symbol with my left click just move the symbol, but I can't put it in the symbol palette.

Thanks in advance for your anwser ;)