N-Puzzle

The correctly placed tiles are marked in blue, while the blanks are marked in red.
The user's options are:

• Simple click. By clicking around a blank you can swap this tile into the blank position and swap the two. Clicking is not possible in positions not adjacent to the blank.
• Shift-click. Puzzle restart.
• Control-click. Opens a popup dialog that allows editing of the game's parameters : dimensions Ν and Μ, problem solving animation delay in msec and refresh period (see below).
• Alt-shift-click. Start/stop os automatic puzzle solving. The solution is animated, that is the consecutive moves of the blanks are shown. Every move may delay a while and this delay parameter may be edited as before. In the case of big puzzles whose solution demands a lot of moves, the user may employ a bigger refresh period that only refreshes the puzzle view after a number of steps.
• Control-Alt-Κλικ. Repetition of the last completed sequence.
• Control-space. (Does not work in all systems because Java does not cooperate fully with keyboard drivers) Automatic execution of the next move toward the final solution (the blank will move one position).

Known bug
The system may be stuck after restarting of the puzzle with shift-click.