A Unit Queues a Research Event?

[Goober4473]

I'm having a minor bug that it would be nice to fix if possible.

I have a pait of upgrades, and researching one dissabled the other. I have a trigger that dissabled the other when one begins research, and a trigger that re-enables the other when one is canceled. All is well, until you queue up another research, and then queue up both of the exlusive ones behind it. Then, it allows both to be researched.

This is minor because the effects won't stack, and researching the second will either do nothing, or replace the first one, but it wastes money, which is kind of lame.

So, is there a way to detect if an upgrade is put in the queue?

 

[Accname]

no its not possible, but i think there is an event "unit begins research", just check whether the contrary upgrade has been researched already and cancel the order if so.

another possibility could be to give the upgrade techtree requirements, for example upgrade A needs the requirement DummyUnitB.
DummyUnitB is created for every player at map init and removed if upgrade B is researched. thus upgrade A cannot be researched anymore.