Thank you for taking your time to file this bug and help making Ubuntu better. Are you sure that when you select multiple files and choose Properties from the right-click menu, you get the properties window with Back and Forward buttons? As far as I checked it happens only when you select a single file from the playlist and open its property. When multiple files are chosen, then the properly window displays only the common properties between them and not a Back and Forward buttons for sure.
Also, I couldn't reproduce your bug on Rhythmbox 0.11.5 on Hardy. Back gets disabled when the first file on the list is reached and Forward gets disabled when the last file on the list is reached.
Thank you for taking your time to file this bug and help making Ubuntu better. Are you sure that when you select multiple files and choose Properties from the right-click menu, you get the properties window with Back and Forward buttons? As far as I checked it happens only when you select a single file from the playlist and open its property. When multiple files are chosen, then the properly window displays only the common properties between them and not a Back and Forward buttons for sure.
Also, I couldn't reproduce your bug on Rhythmbox 0.11.5 on Hardy. Back gets disabled when the first file on the list is reached and Forward gets disabled when the last file on the list is reached.