This is actually two questions in one:
First, when you write your XAML and Intellisense fails to recognize the type you want to use (in my case, Array), what steps do you go through to figure out what's going on? I initially look over my XML namespaces to make sure that everything looks like it's in order. If it's a CLR type (not one of my own), then I end up checking Google (and usually can't find what I need).
In this case, my query was "XAML WPF namespace missing Array", which tells me, as I had suspected, that Array is in http://schemas.microsoft.com/winfx/2006/xaml, but it doesn't show up in Intellisense. Why is that?
All of the examples I see are in a Window or Application, not in a UserControl like mine. Is that related to my problem?
Ok, I guess that was technically three questions. :)