There's two things you could want to do:
1. show only the two main menus, and then have submenus
2. show the main menu, a separator bar, the sub-options, and repeat that. This solution covers door #1:
In popups, a . defines a sublevel ina menu. 0 . means a main menu, 1 . means a submenu, 2 . means a sub-submenu, etc. Your dots are screwed that way.
Also, when hiding a window, all you need is to specify which one, you don't have to tell mIRC the size parameters of the window. The same goes for un-hiding it. You only need to specify those parameters when creating the window.
Try this:
menu @config {
Hide Ventana
.Snotice : window -h @snotice
.Operserv : window -h @operserv
.Chanserv : window -h @chanserv
.Nickserv : window -h @nickserv
.botserv : window -h @botserv
.Servernotice : window -h @servernotice
unhide Windows
.Snotice : window -w @snotice
.Operserv : window -w @operserv
.Chanserv : window -w @chanserv
.Nickserv : window -w @nickserv
.botserv : window -w @botserv
.Servernotice : window -w @servernotice
}