Can you provide a screenshot? 'Coz my faster application manager uses it's own generic greenish wallpaper.

Edit: Aaa! There's an update for FAP which now seems to take the picture from theme. That's the same wallpaper that's being used for inbuilt application manager and changing that isn't possible for end user (it's not desktop wallpaper, but in Pleego's case it's the same image I used for homescreen background also among with clock, mediaplayer and lockscreen backgrounds).