System: xubuntu 13.10 (32 bit, fully patched). Package: xfce4-display-settings, provided by the package xfce4-settings 4.11.0-1ubuntu1 from the Ubuntu repos. Condition: When launching xfce4-display-settings (either from Applications Menu > Xfce Settings Manager > Display or through a CLI) then a new large non-transparent black pop-up notification panel also appears. The pop-up details summary information on the current display output device. It is positioned in the middle of the bottom of the screen on top of any other screen items. Issues: 1/ The pop-up blocks the existing bottom Xubuntu Desktop panel – including its launchers – from view and from user access. This is problematic in particular on smaller (eg, 10") screens. 2/ The pop-up is permanent until xfce4-display-settings itself is closed. It cannot be dismissed (there is no Close button on the pop-up that can be clicked). It cannot be dragged away to give access to the Xubuntu Desktop panel. 3/ The pop-up does not obey the global Desktop preferences settings for notifications that have been set in Applications Menu > Xfce Settings Manager > Notifications. Proposed solution: 1/ Add a close button to the pop-up. 2/ Enable dragging the pop-up. 3/ (Perhaps longer-term) Make the pop-up obey the global Desktop preferences settings for notifications. Possibly also: Make the pop-up optional.
Since the pop-up isn't a notification per-se but rather an identification tag, the only real issue I see is it blocking access to the underlying panel. Not a show-stopper but quite bothersome. Both the close button and drag-n-drop solutions are reasonable but I don't agree it should be implemented as a desktop notification. I suggest mousing-over the pop-up causes it to jump to the opposite screen edge (top or bottom).
The identification popups can be shown/hidden from within the settings dialog, so this bug has meanwhile been fixed.