I made a .jsx script file that create and manage a menu item inbetween ID main menu.
I put it in Startup Script folder and everyhting works.
Why if I put there the same file exported as .jsxbin it doesn't work?
Your jsx contains a #targetengine directive to create the engine that allows you to work with menus.
Unfortunately, you can not use a jsxbin to launch a target engine on startup.
You'll have to use 2 scripts. One is a jsx that contains the targetengine directive and loads your jsxbin script (using $.evalFile).
Thanks a lot!