Simple timeline is ported over to goocanvas, at least to the point where it's usable. There are some graphic glitches that I'll fix later, and I want to improve the code which handles external drag-and-drop (currently sources are always appended, I'd like to have some interaction which allows you to drop sources anywhere). I'm switching my attention to the advanced timeline.

I'm probably going to gut all the existing timeline code completely, because most of what's there is redundant with the facilities goocanvas provides. For example, zooming is easily handled by goocanvas's scale_x property. In addition, scrolling is taken care of automatically if you use a gtk.ScrolledWindow, so the layers of indirection are really, really unecessary. I can handle the informational messages directly in goocanvas...basically the structure of the timeline will look like this (more-or-less, parent classes in parens, trailing * indicates more-than-one).

* Generic timeline widget (gtk.ScrolledWindow)
**SimpleTimeline (goocanvas.Canvas)
*** SimpleSourceWidget*
**ComplexTimeline (goocanvas.Canvas)
*** PiTiViTrack*(smartgroup)
**** PiTiViSourceWidget* (goocanvas.Rect)