Auto Hide is only available for Fixed Position panels, the option doesn't appear for Freely Moveable ones. (same in latest svn also, -r23859)
Yes. This is a design decision. Only panels on the edge of the screen can autohide, so in that case you can just as well use a fixed position. It's much harder to implement properly for freely movable panel, so I didn't. If you really want this, you can reopen the request and change it to an enhancement request. Personally, I am not really interested to work on this, but maybe someone else will be.
Ok, reopening as enhancement request. It seems more people want this. I'm still not going to do this myself, but maybe someone else will pick it up.
*** Bug 2609 has been marked as a duplicate of this bug. ***
just as a followup: now that i've been using 4.4 for a while i don't much care for being able to move the fixed position panels around. it's not perfectly exactly where i wanted it but that's ok :)
I'm closing this bug. Autohide for floating windows is not user friendly and in the new panel you can snap the panel on every position of the screen (and then snapping will work).