Have a custom tooltip on customly drawn component "controls"

In Karamba3D, there are custom component “controls” such as the button, radio buttons and the labels in the following screenshot:


I have managed to create the same “controls” by overriding the Layout and Render methods in the Attributes of the component. I can’t figure out how to make the custom tooltips show when the user hovers over the “custom” controls however. How would this be done?