How does one start making a credit card applicatoin that may edit it's own feel and look? Can tweak its very own XAML files? then reload them. I am thinking a notepad-like text editor, not really a visual designer.

All of the event/code could be bound immediately after display from an "iron" scripting language.

This can be done anyway you would like, just completely abstract the display engine all other logic including event bindings and more. The information-format for that UI whether it is XAML as well as an performed JavaScript blob then does not matter.. what matters may be the engine can offer a consistent interface for passing occasions to the logic, no matter the UI condition.

To get this done you can produce a self modifying engine that utilizes an electric train engine definition to create an electric train engine for self-modifying UI definitions :P

I've written a couple of prototypes where I put a XAML document on the web server and download that XAML and load it into an ElementHost control on the WinForm form. It labored very well.

I haven't attempted connecting up event handlers yet though.

Update: This blog publish by Take advantage of Relyea has more details you could ever need to know about connecting up occasions to downloaded XAML.