draft

8 queen 1 game simple to proggramer

64 squares
   + bgcolor
   + isOccupied
   + isAvailable
   + stateChanged

InitBoard() : draw an empty board 
repaint() : repaint square which state has been changed

toogleOccupied(i, j) : toogle occupied and then call toogle state
toogleState(i, j): toogle state

record(i, j): toggleOccupied of [i,j], toogle isAvailable of all necessary squares