Currently the only way to shuffle through songs is to click the shuffle button on a artist, album, etc... This loads the selected music into the now playing list.   The problem with this is you cannot enable/disable shuffle during playback without reloading the whole now playing list. Not really an issue with single album/artist now playing lists but if you have built a long now playing list you have to rebuild the whole list or save it as a playlist then shuffle it.   Personally i like to