#141 display problem with the data editor for time values

[Emmanuel Vincent]

When I open the data editor for a layer of time values and edit the label for one instant in time, this instant disappears from the displayed table of instants and labels. The instant and the updated label are not removed from the annotation though, since they reappear when I save the annotatation then close and restart Sonic Visualiser. I am using Sonic Visualiser 1.5 on Windows XP.