Multiple windows on one form

What's the best way to program a window interface such that as a user triggers an event, the form loads another window on top of it

I am thinking of using panels that covers the entire form and layering them. Then bringing certain ones to the front or back to create the effect it's loading a new window. But I am not sure how to get them all to be the same size if I resize one of them during design. I have 10 panels.

Thanks