It appears that adding multi-window support prevents gmmp from being successfully installed on devices running versions of android earlier than 2.1. Due to this, the version of GMMP on amazon now requires 2.1+. Amazon does not provide the details on who has purchased GMMP, so if you are on 1.6 or 2.0 and purchased GMMP please send an email to firstname.lastname@example.org and I will help you get updates. Users on google play will not have to do anything because it supports multiple apks. Users who do the direct download should now use the PRE-2.1 version linked on the right if you are on a device running 1.6 or 2.0.
-Fixed an issue where GMMP would not receive headset/remote control button presses
-A black background is now used instead of the gradient background (Prefs -> UI -> Background)
-Expanded notification option disabled for pre jelly bean devices
-Added an 'Always on Top' option for the lockscreen. Turning this off will allow text message dialogs show up over top of the lockscreen player
-Playing/enqueuing an 'All Songs', an artist or a genre will sort the tracks using the sort order used for 'All Songs'
-Playing/enqueuing an Album will sort the tracks using the sort order used when viewing an album
-Added 'Artist - Album Year' sort option for viewing all songs
-Fixed bug causing equalizer presets to not be created on first launch
-By default gmmp will now continue on to the next file once a single track queue completes
-Minimum crossfade values dropped to 100ms
-Added option to completely exit/shutdown GMMP via back button. (Prefs -> General -> Exit With Back Button)