Custom Property Animation Problem.

Hey there,
is there a way in blender to check if a property has keyframes applied to it?

I have created custom properties. This properties call a specific update function which does some stuff in the scene.
When changing this property everything works as expected.
The problem is, when I key my property the update function doesn’t seem to be executed.
Is this usual?

As an alternative solution I wanted to write a framechange handler that loops through animted properties. But how do I know if a property is animated?

This is a good question, I couldn’t figure it out, maybe ask in devs irc?