When using the Window Buttons applet, provided by the Gnome Window Applet package (link available in my older report, regarding the Window Title applet) the panel itself becomes a target to the controls.  Once there are no more windows left on the screen, you can see the Window Title applet change to "xfce4-panel".. indicating that the panel is being perceived as a window.. if you click minimize or maximize, it does nothing.  However the close button does work, closing the panel.  You have to recreate it from scratch, afterward.

It also has reverted to an old behavior, whereby it will see the desktop as a target.  In this situation, it attempts to execute the log out action when you hit close.

Not sure if this has something to do with Bonobo/Dbus changes in the neighborhood.

Thanks.