Okay... I have successfully downloaded Dropbox music files to oplayer. I have created a blank playlist, but can't figure out how to add tracks to that playlist. This is the final hurdle. Any help?
I'm not sure what you mean. Do you mean the total time of a playlist or the number of songs?
Regardless, on a quick look, I found this:
I guess you could kind of add up the song lengths. I didn't really find anything better (such as iTunes way of telling you how many hours a playlist will play).