Start of a custom control
Added focus, background color
Added event for when the letter changes
Make it more clear where the custom control is
Use dependency property instead of custom event
Use dependency property for cryptogram letter as well
Create character controls programmatically
Add delete, some cleanup
Added a bunch of comments to explain the code
Pass non-letters through to the solution
Make the formatting more similar to original
Added control event for letter changes
Display with custom controls and hide help text
Fixed extra padding issue
Hooked up letter changes
Removed unnecessary dependency property