It's such a minor topic that it nearly doesn't deserve an own thread .
But is it a difficult change to remove the smoke feature when a Geothermal is built on it? So unit creator can decide where the smoke comes out? (Like in Starcraft)
Having looked at the code, I say that it's not as easy as you could have thought, because a geovent is essentially a feature, and detecting whether or not it has a building placed over it could be tricky.
Edit: As the position of a feature and also of a building can be determined would it be possible to remove/add (but i guess removing is a bad idea as it would have to be added new after destroying the geothermal) the feature which groundplate overlaps with the gheotermal groundplate as the building is finished or destroyed?