there is no way to focus there using keyboard. It _can_ be shown (that is, hide all else), but it is not focused. suggestion: showning the desktop should focus it. Unfocusing could be done either with same key like focusing, or by window-switching (alt-tab). Also, focusing the desktop applies to all workspaces... That is: all other workspaces lose their currently focused window. Maybe anything with the (sticky?) xfdesktop applies to all workspaces (focusing too!), and this is not right... what is being done in one workspace should not apply to other workspaces.
Hmm, not sure of the best way to do this. Olivier, any thoughts? Maybe something like the xfce4-popup-menu app you made for the desktop menu, which can be bound to a key? I don't really like that one too much, though...
Do other WMs/DEs give the user a method to focus the desktop via a key combo? If so, how?
Oh, sorry, that bug is fixed and should be closed.