I don’t know what to tell you. This code works. I really don’t understand the issue and your screencasts doesn’t help to understand. In console I see you have the correct output, but you never show how you click the checkbox and what happens to layers
Sorry, but I don’t think I can help you any further
So why do you always pass true to _show?
My friend Karmalakas.
I am very sorry for my many questions.
I am very sorry, my friend
Finally, the code worked as I wanted
Please accept my apologies for my many questions, but you have helped me very, very much.
Regards 
Mohamed Fathy… 
thank you pro…
The solution you provided works too.
Regards
Mohamed Fathy…