[yildi]

Thanks a lot RandomCoder for your suggestions. The first solution seems difficult to me because my panels are not always organized with the same structure and I do not know how I can suppress or move a line drawn in the foreground (if I understand well, they are not objects that we can easily manipulate - like in java forms, for example).
The second suggestion can be a solution. I will check if I can attainan esthetically interesting result with this trick ;-)

Best regads,

Murat