I installed XFCE 4.4 Beta1 yesterday, it really works fine (great work!), but I think the Panel should get some minor tweaks:

1. It should be possible to configure where the arrow for submenus is placed. For vertical panels I would prefer having the arrows besides the buttuns and not above/beneath.

2. Perhaps somethink like a "stacking"-option would be nice. So you can have 2 panels at the same edge of the screen without overlapping. You can of course make one panel to be freely moveable with the current code, but with this option the borders are not set automatically (You have to set the borders yourself).