6 x 6 magic squares
A mouseclick on any number of the green-bordered square ("number-pool") moves this number into the first empty
field of the red-bordered square ("magic area");
a click on any number of the magic area brings the number back to its original place in the pool.
When "show" or "quick" is activated, a backtracking algorithm will continue the search for a solution; interruption can be caused
by clicking the option "mouse". When a solution is found, the algorithm will stop, and in that case, a search for a next solution may be continued with the corresponding button. The blue-bordered square always contains the last found solution.
The delay (in milliseconds) regulates the frequency of image output, if "show" is activated.
A magic square of size 6 x 6 is to be constructed, (with additional properties: nine of the 2x2 subsquares have equal sums and the inner 4x4 subsquare is pandiagonal).