Upgrade trigger?

What i want to do is basically this

Building A
has the following upgrades availbe
Upgrade 1
Upgrade 2
Upgrade 3
Upgrade 4

now when you pick any of the upgrades to reasearch, it cancels out the oppurtunity to research any other of the upgrades
for instance
If i choose to upgrade to Upgrade 1, it would not allow me to reasearch upgrade 2, 3 or 4
Thanks in advance

sry for bumping this thread.. but does anyone know if it's possible because i don't think it is :(

You could use dummy abilities instead of plain upgrades, and remove them when one is used...

The action you need is:
"Player - Set max research level" use 0 to disable.

cool thanks a bunch