* Put in alert panel warning user if a block bitmap is not found.

* Remove Document menu item, and any other extaneous menu items.

* Someone has suggested making each piece a unique color.  This helps
  at the higher levels.

* Someone has suggested that the play of the game be changed so that
  you move to a higher level after you have completed so many rows on
  the current level.

* Should the number of rows and columns be changed to X and Y,
  respectively?