how does the tool tip control "talk" to the other controls on the form?

I was interested when I just used the toolTip control for the first time because it caused an additional property to appear on the button that was already present.

The ability to write user control that is "aware" of the other controls on the form is something I'd like to have in my bag of tricks.

Can some开发者_如何学Goone give me a pointer to if this is reasonably straightforward and the starting point for learning how?

You have to implement IExtenderProvider.

http://www.codeproject.com/KB/dotnet/iextenderprovider.aspx