After the switch to using MPD as a backend to the mediaplayer application via the existing abstraction provided by libqtappfw, testing shows that pulling a USB drive while in use by MPD / mediaplayer does not get handled well.  While the MPD and the app do not crash, the following is observed:

• The playlist in the mediaplayer clears (good), but metadata for the currently playing track is not (bad).
• The mediaplayer does not respond to pause input for the now dangling track.
• There's a chance the previous issue would maybe fix itself with a new playlist coming in from MPD updating state, but in my tests MPD is unable to update when a USB drive is (re)inserted, an error about failing to set up inotify on the newly mounted directory under /media is logged.

For now I'm leaving this as a low priority as it is not an immediate concern for the demo application, but if AGL keeps using MPD or the Qt demo mediaplayer, someone may want to investigate further and attempt to remediate the issues here.