Good article?

Looks like this may be similar to what I'm looking for:

WPF Tutorial -- A Visual Collection

Interesting quote:

"and we can't use any of the normal controls that do (Panel, ContentPresenter, etc...), because only Adorners can be placed on an AdornerLayer."

Does this mean I can't use my template at all on the Adorner layer? How come MS was able to put Rects on it? Shapes aren't controls, I guess... but I've also tried adding Lines and Ellipses and they don't show in my VisualCollection either! ARGH!

I've now read that entire tutorial, and I still have no idea what's going on. It's using a ContentPresenter instead of just the VisualCollection. I can't get the Adorner to show anything, seemingly, unless I put something in OnRender. What's going ON?! Going to simplify my whole project and see what I can find.