Is there a tool to do this job?

This is what I am looking for: Something like a MDI component where you can have a window inside another window. I don't want to use MDI (I want to try something new). The window on the inside doesn't even have to be another window, just a panel with some controls on it. However, the user must be able to load different panels into this space.

I'm sorry if this is confusing, I am new.

Thank you.