Wow thats new to me!

padmalcom => thanks for the advice
superku => thanks for the advice/correction, I will try to advance with it but it looks complicated.

Maybe I will finish by simply put all the j1.visible=off;j2.visible=off;j3.visible=off; [...] j50.visible=off; If I don't succeed i think it will be a lot more accessible.

have you had a look at draw_text()?

Just looked at it in the manual,
but I don't need to just draw a text. Thanks anyway, maybe I will need it some day.
By the way, i found a "concrete" example of the function of superku and its more explicite in practice.

edit : just wait.. is the function of superku just for render a text visible or not ? omg I'm lost for now maybe i'll take a break.

re-edit : I was trying to pass by a string in order to put the name of a panel and render it visible or not by adding .visible=off;
I take a break.