Builder Structure Page

[TeroTron]

I'm making a rts map and my problem is i can't figure how to make a builder with more than 2 pages of structure.
Example the Builder can initially build melee buildings if he casts a "Next Page" Ability it will allow him to build custom structures by me.
so, anyone got any idea to make this?

Update:
I know that i can just make a morph ability for that builder but i want it to be neat that they don't cast it
i mean when they are repairing and when i cast it, it does not stop them from repairing

 

[Pinzu]

You don't want to interrupt repair... Really?!?! Then you could either check the last order of the worker or create a hidden worker doing the actual orders. But honestly why would interrupting repair ever ever ever be an issue?

 

[TeroTron]

To make it neat?

 

[TeroTron]

Its a RTS Map so it requires little macro
example of situations
The player builds a altar of kings then presses for next page then holds shift and builds that structure

 

[Pinzu]

Nobody will care or notice. I've got no idea how to solve this, but I can suggest having two different workers. But in my opinion problems such as these are just wasting away at actual progress in ones map.

 

[TeroTron]

Well i got no choice then, anyway thanks for trying have a rep