Cannot play a timeline with only audio or only video
@jeff
Submitted by Jeff F.T. Assigned to Alessandro Decina @alessandro.d
Description
to reproduce, start a blank project, import an ogg vorbis or MP3 file or two, drag it/them into the advanced timeline.
You can add them to the timeline, but you cannot play the timeline.
Imported from https://bugzilla.gnome.org/show_bug.cgi?id=430694