MultiDocumentPanel uses an internal MDIDocumentInternal (DocumentWindow) to wrap Content Components, but I want to wrap them with a different DocumentWindow and I don’t want to change the original MultiDocumentPanel code. What should I do?

Hmm. I guess to do that I’d have to make the internal class public and add a virtual method to the MultiDocumentPanel to allow you to create a custom subclass of it if needed… Not difficult to do, I could make those changes for next time. In the meantime, I’d say do the same, or hack it some other way!

Thanks, I will use a subclass of DocumentWindow, at next release I can make it a subclass of MDIDocumentWindow.