Primordial Ooze

Konfabulator pretty much requires Photoshop

So, it looks like Konfabulator is nothing like XAML and you basically need to use Photoshop to do anything that looks good. If you're not skilled at using photoshop then you're pretty much up the creek.

What they offer is a standard interaction interface, ability to fire off timers, handle events, and otherwise interact with the user. They also nailed transparency effects and image compositing which takes the alpha level from image into account when performing the blend. Finally, it looks like they provide scaling and rotation transformations (which is how the second-hand animates in the World Clock Pro.