Ok, here comes the nasty nestharus review on your resource because I felt like making you mad at me too ;p
static boolean enabled
Useful for things like prevent units from being healed for a period of time. Good job.
JASS:
* - Heal.INSTANT
* - Fires on instant heal events.
* - This would be used for systems like:
* - Texttag Displays
*
* - Heal.TIMED
* - Fires 32x a second during a timed heal.
* - This was only added for a sense of
* completeness. It may be useful.
These are useless. The only thing you need is ANY. This is useful for things like modifying a heal as well as displaying texttags. However, if you are going to do healing modifications, you should support healing types, that way the user know how to modify the heal. This would also mean that you could have 4 healing effects on a unit, meaning that you'd fire ANY for all 4 of them. You'd also want to show the texttag for the combined healing.
Look at my DamageEvent stuff in order to see how to properly implement this to support cool things.
The only way this library will ever be useful is if you code spells as a variety of effects. For example, one spell could have a healing effect + an armor boosting effect for a period of time. It'd create the healing effect using your heal system and the armor boosting effect using perhaps an incoming damage modifier.
Really, I'd almost implement a healing system by dealing damage of type HEAL or w/e that way it could run with the rest of the damage stuff. This would allow you to easily support healing types, like undead healing, which does in fact damage living targets.
I actually think that healing should only be done as damage now >.>. For example, if a unit has 33% spell resistance, they'd also resist healing spells. Having your thing not run on damage requires all of the same events to be registered for both damage and non damage types, which makes everything harder and messier to do.
So, in the end, my verdict is that this resource is not flexible enough to be a general system. If it was made to be flexible enough, then it'd be a copy of damage modifiers that just inverts the damage (-damage instead of +damage) ;\. Simpler maps would just use SetWidgetLife and advanced maps would use damage modifiers. The Heal system doesn't really fit in anywhere >.>.