TODO (In rough order of priority.)

Extend (or use a pattern!) SimplePatch and have a rollback method - an 
undo(int i) method that takes the Patch back to a former state - useful for playing 
with difficult tilings. Have a corresponding redo(int i) method. 
 
Get colour changing to work properly!

Allow tiles to have images on their surfaces (you can now, see Trimorphic, for the idea). 

Refactor TileView. Add a RowsCollection object that handles rows of Lists,
and a SelectableCollection which allows objects in the collection to be selected (on or off).
Selections by dragging. 

Write beans stuff for tile UIs. E.g. to turn Ammann bars on. Use Jython?

Add deflate/inflate to Penrose tiles. Write PenroseTiler. 
 
Fix deficiency in pentomino_Z and tetromino_skew symmetries. 
 
Render dotted line on penrose.LB.

Serializable. Improve Save As.. and Open file for Alhambra/Viewer2D.

PNG save format.

Find out about Postscript format. Save option for converting tilings to Postscript. 
(Use Print to file option on Linux.) 
 
AlWAYS TODO

Write more javadoc.

Write more building-block tiles!

Write more unit tests.