onHover() : how to disable call to ShowDefinition depending on the context

[Clams]

I’m playing with the new event onHover to display a popup with some information and I’m running into case where the ShowDefinition default function is also called at the same time: the ShowDefinition popup appears for half a second before being replaced by mine.
I don’t want to disable completely the ShowDefinition because I like it when it’s not in the context of my plugin, but I’d like to make sure it is not called when I my plugin will generate its own popup: any idea on how to do that ?