I suggest that you copy TFPGMap and replace KeyCompare with something else more specialized with your objects
The KeyCompare was the reason I decided to ask instead of directly creating an issue.
Replacing it is not an option? (Although I don't know how could be done.)
This way would avoid future problems. It is weird to have a
generic class that is incompatible with a large portion of the language.
similarly to what was mentioned here.
The source cited in the commentary was moved somewhere else, I believe.