Upon track advancement (through any means) the next track that starts playing is selected from the source that is currently selected, and not the one in which the previous track exists.

For example, user starts playing a Track from the source 'Music Library', and then switches to view the a different source like a playlist. When the Track has finished playing Banshee will choose the next track to play from the playlist that is now viewed, and if the playlist (the source) has no tracks playback will stop.

Choosing the source from which tracks are being selected based on which is viewed is an inconsistency with, as far as I can tell, every notable music player. Not good.

And on top of that, this way of source selection limits the users freedom to browse which ever sources are available while not having to care about track selection.

I propose that the source in which the user starts playback should stay the source until the users starts playback in another source.

That is, as for now -- when queueing is possible it would also have to be decided if the source should stay as that of the before-queue source, or, if the queued track is selected from a different source than the before-queue active source, should the after-queue source be changed to that different source? But I think that would need someone more educated than me to discuss.