Personally, I'd also like to have some way when creating custom windows that prevents menu items not specific to that custom window from being there as well. This would allow your custom window to only have specific menu items when someone else uses it even if they have other scripts that insert menu items all over the place instead of specific.
This could be a switch in the /window command or else a menthod in menu { } to prevent other menu items from showing...
menu @mycustomwindow {
haltdef
OnlyMyMenu
.AndMySubmenu:Do this
}
It's fine to make your own menus more specific, but if you want to distribute your script(s), you can't control what other scripts users use.