U can use the ppc shown in the desktop as if it were the ppc and You will be actually usisng the ppc..
Imagine typing a long word doc... in the ppc it would take forever, but this way, you're still using the ppc trough the desktop, using the desktop keyboard...it saves time and effort...To copy the screen image use the prtscr key , it copyes an image to the clipboard and can be pasted to any image editor.... then just crop the image to the size you want...and save it.