How to create a button that brings up another menu in a Unit?

[MalfunctionStrmrge]

Y'know how in some maps, a Hero will have a button in their command box that brings up another menu with castable (not learnable) spells? How exactly would I be able to create something like that? Is it an ability or what?

thanks in advance!!

 

[watermelon_1234]

I'm not sure, but I think you're talking about the Spellbook ability.
If you want to learn more about it, there's a nice tutorial here .