How to close a dialog form using pictureBox instead?

[Hiner]

I am now using VS2005, in C++ environment. I am working on a windows form application that has a main form and can create and show a new form as a dialog form using the command:

StartMenu_Exit ^ ExitDialog = gcnew StartMenu_Exit;
ExitDialog->ShowDialog();

in which "StartMenu_Exit" is the child form that I have prepared. An instance of it should be shown as a dialog form.

In "ExitDialog" I have buttons that can close the child form and return "Yes" or "No" values to the main form. Now I want to do similar things with pictureBox instead of buttons. But I have yet found methods that can be applied to pictureBox to close the child form without closing the parent form as well. (as for returning values, I think I have some ways to do so)

Does anyone has ideas on commands that can close the child form and return focus back to the main form? Any opinions are welcomed.