In XFCE 4.6 it was possible to put a floating panel at screen top or bottom. Starting from 4.8 when you try to move panel to screen bottom it becomes docked. This is a major loss of functionality because having a floating panel at screen top/bottom makes it possible to maximize windows to the whole screen with panel not stealing viewable area. This makes it almost identical to Avant or Mac. The workaround for now is manual editing panels.xml
Sorry, not panels.xml but ~/.config/xfce4/xfconf/xfce-perchannel-xml/xfce4-panel.xml
You can also disable struts with: "xfconf-query -c xfce4-panel -p /panels/panel-0/disable-struts -t bool -n -s true".
Well you can disable struts and this is just the way the new panel works, so no real regression here.
There's no doubt that I can disable struts But the users can't, unless they learn Xfce internals or go to this issue That was the point of the issue
It was already planned to make this option more visible in 4.10 and it will also be noted in the manual; when i find time to write it.
*** Bug 7201 has been marked as a duplicate of this bug. ***
Opened bug #7202 for the configure option.