[Cuis] Morph instance specific mouse and drag methods

[Ken Dickey]

Some reasons for using properties for instance specific behavior:
  - Morphs already have properties (no new classes)
  - UI operations can be a bit slow but are fast relative to humans
  - No change to VM dispatch mechanics
  - Current usage does not change hardware event -> message dispatch mechanics 

Much of what I am interested in relates to direct authoring via drag-n-drop pallets and fill-in-the-blank or simple method extensions.  I am not sure where I would use instance specific behavior outside of the UI.

One thing to think about is that common patterns can use "threaded code" which is very efficient.  For a specialized common cases the Scratch solution is very attractive alternative to/as a mini-language.

More playtime as I get a chance..
-KenD