Android Question B4A SUDOKU GAME BOARD

Sub draw_board
cnvs.Initialize(cover)
For i = 0 To 3
    cnvs.DrawLine(0, ystep*3*i, board.Width, ystep*3*i, Colors.Red, 3)
    cnvs.DrawLine(xstep*3*i, 0 ,xstep*3*i, board.Height, Colors.Red, 3)
Next

For i = 0 To 9
    cnvs.DrawLine(0,  ystep*i, board.Width,  ystep*i, Colors.black, 1)
    cnvs.DrawLine(xstep*i, 0 , xstep*i,  board.Height, Colors.black, 1)
Next
cnvs.Initialize(board)
End Sub

Sub board_Touch (Action As Int, X As Float, Y As Float)
Select Action
    Case Activity.ACTION_DOWN
        Dim st As String
        sel_i = X/xstep
        sel_j = Y/ystep
        sel_pnl.Left = sel_i * xstep
        sel_pnl.Top = sel_j * ystep
        st = a(sel_i,sel_j)
...