Click-through frames over SecureUnitButtons possible?

[Iza]

Hi,
I'm currently trying to provide tooltips for custom debuff icons in VuhDo and I'm having a slight issue:

In order to have "OnEnter"/"OnLeave" functionality I need to make them "Frames", not just a "Texture". So tooltips now show with no problem.
The problem is that these icon frames are overlaying my "SecureUnitButton" and they are eating mouse clicks if I click on the icons (though I have set enableMouse="false").
What I'd like to have is onenter/onleave but mouse clicks being passed to the UnitButton below.
I had a look into how Blizz does this in their raid frames (actually they set OnClick to function "PassToParent") but this is not possible for custom addons (= tainted execution path).

I could possibly make all debuff icons "SecureUnitButtons" themselves and set spells up the same regular buttons, but I think this would be overkill in terms of memory and cpu usage.

Any suggestion highly appreciated, thanks in advance,
Iza