Gary,
 
I have done a little with Polymorph and am quite impressed.  A small usability suggestion for the examples is to include comments with the text on a line by itself.  It is a lot easier to execute something formatted as
 
"
     ThisOrThat example
     ThisOrThat someOtherExample
"
 
than it is the  (very common in Squeak) "GoAhead iChallengeYouToSelectMe andMissTheQuotes".
 
On to more substantive things.  TEasilyThemed is a big help, but some model and/or presenter classes would help.  Consider a list.  One has to define an aspect for the selection index and initialize it to zero.  Similar comments apply to trees, with the added wrinkle of wrapping the nodes with appropriate objects.
 
Dolphin's MVP framework creates default models that can be replaced.  One weakness of the defaults is that they can take significant time to create for substantial objects.  I hacked around that, and we could easily design it out of anything that we build.  Dolphin lists and trees treat their selection in terms of the object selected rather than the index.  One can get and set the index if needed, but it is not generally as interesting as the object behind the selection.
 
One good thing about specifying the aspect is that one can can connect a view to an aspect of any model.  Dolphin allows for the same flexibility via value adapters and type converters. 
 
Does TEasilyThemed include helpers for creating splitters?
 
Bill