Hey seven....first of all thanks for comment... look you have to get Screenlets...it has a screenlet called Now Playing, that shows the albumart in the desktop...I had some problems to use it with Rhythmbox but it worked fine with Exaile...if you want get some themes you should go to gnome-look.org...they have good stuff there!!!... I hope this helps!!
thanks for your kindess I intalled screenlets, but nowplaying doesn't work. Through google I found reason why it doesn't work. Now I'm using media cotrol of AWN. If you have curious about it, show my screenshot. [link]