How can I get the handle to a Canvas/PictureBox?

Question

I am developing an application which uses the Math Input Panel that comes with Windows 7. The input panel allows users to draw math (using a pen or mouse device) and after recognizing the symbols it sends back MathML(xml).

However, I need to get the image of the recognized math as well. I am able to get a window handle for the input panel control using the following code:

    [DllImport("User32.dll")]
    public static extern Int32 FindWindow(String lpClassName,String lpWindowName);

    ...

    micautLib.MathInputControl mip = new micautLib.MathInputControlClass();
    mip.Show();
    int hWnd = FindWindow("MathInput_Window", "");

Does anyone know how to get all the handles and names of controls inside a window? (Microsoft Spy++ doesn't show anything more than the parent window handle so I am assuming the Math Input Control is composed of only one window)