Custom paint on Form caption (C#)(repost)

I need a sample code that will do custom paint on a .NET form caption, see sample [login to view URL] I don't need buttons or to accept mouse events just the drawing on the caption BUT as different from the above link I CANNOT override wndproc() becouse my code cannot inherit from the form class, I don't have access to that code Background: My code (guest) work as a plugin in a larger program (host), the hosting program create the form and set the caption of the form and also call my guest code, my guest code has access to the form object, to the public properties and method of the form. What I need is to add custom caption drawing on the form caption, I cannot change the form caption as this will be changed back by the host application. What I need is a sample code that will do similar things to what the above link does but without the need to inherit from the form. I guess this can be done by using WINAPI and get the wndproc address.