Vista - Build My Own Intellisense

Inside a winforms textbox, I wish to build an intellisense process, just
like in the Visual Studio IDE. Is there any framework, or existing
technology inside Visual Studio to aid in this process. Basically, where do
I begin? I am building an If Then string in logic. An example:

If [MyForm].[MyField1] = 1, Then [MyForm].[MyField2] = 2

So after the user types If and hits the spacebar, a combo box drops down
that has in it [MyForm], [MyForm2], etc... Is this going to be a nightmare
to build?

Derek