Is this possible?

I searched the forum but didn't come up with anything.
I need a trigger, that when a hero learns and ability, if its one he shouldn't learn yet, the ability is unlearned (not removed) and the hero is given the skillpoint back and a message to the hero is given.

Something like this:

There would be a few uses for this trigger.

1. Lets say you have a fire&Ice based hero. hero has 5 skills. 2 are Ice (we'll call them I1 and I2) and 2 are fire (F1 and F2) and one is Ice/Fire (I&F) mix.
You don't want the hero to be able to learn I2 until he/she learns I1. And you don't want the hero to learn F2 until he/she learns F1. And lastly you don't want the hero to learn I&F until the hero has F2 AND I2 to at least level 2.

2. You are making a campaign/rpg and you want the ability in the menu so the player can see it exists and what it does, but you don't want the hero to be able to learn it until after an event.

(PS. If anyone does figure out how to do this, then I don't care if you take idea 1 to add to a map, because it sounds cool but I don't have a current project planned where I would use such a hero.)

hm...

What are the effects of giving a Hero ability a Tech requirement? You could make (in the fire/ice example) F1 activate (via triggers) a dummy upgrade that F2 requires, and F&I could require upgrades activated by F2 and I2.

I use that method to solve problem 2) for an activated normal ability (sub-skill in a spellbook offshoot). The ability summons a bird, and requires an upgrade titled "Must be outside." Not sure if this works for hero abilities.

Well that would work for a few things, but I am working on a current project which that idea would not work. Unfortunatly I already thought of that and yes it would work for the above EXCEPT I don't think you can put "Level 2" abilities in the requirement (example, for I&F you need level 2 I2 AND level 2 F2). But I haven't tested that as it does not match my current needs.

Change those damned save game triggers to they work on non-blizzard signed map. grrr stupid blizzard grrr stupid programmers.

And how is this statement benificial to my question, or solving my problem? From what I can see this statement has absolutly no relevance to my question because even if you could use save game triggers it wouldn't help me any.

Er...why won't dummy upgrades work again?

Event - <hero> learns a skill
Condition - skill type of (learned skill) equal to <hero skill whatever>(may need to go into jass to compare hero skills)
-level of learned skill equal to X (2, however, if this is where the problem is with "learned skill" then keep track of the level of each skill whenever they train it)
Action - set upgrade level for "Must have F1" (a renamed upgrade) for player X to 1


Then have your fire 2 require the upgrade "Must have F1".

Newhydra yes that would work. But as previously stated, that doesn't fit my current needs. Can anyone help?