how to use Mdi with Ribbon Control

Effectively, parent-child relationships between forms is made defunct, for a good reason, excluding MDIChild-MDIParent relationships. But this is about forms.

With WPF, there are no forms either. No forms! Windows resemble forms in many aspects, but are radically different technologically. (Long story, but it's good to know how WPF architecture works.)

So, no forms and not window child-parent relationships for windows. I don't know what you are missing. Their are not needed. I would dub UIElement the central type of WPF, and Window is the only top-level element of hierarchy (it has something to do with Windows API, and other elements don't). Your ribbon is not different from other elements, it's placed in a window in the same way as any other element, such as Button, or Grid, or anything...

All right, if you are getting the idea, will you accept the answer formally?

In all cases, your follow-up questions will be welcome, but perhaps you should understand that your questions are moving into asking "how to do WPF development", and this topic is too wide to cover. Perhaps you should just start doing it (but honestly, read on architecture, and, say, visual vs logical trees, layout model, dependency properties, XAML, templating and binding...)

—SA

Do be serious.
Start from the very beginning, say, with https://msdn.microsoft.com/en-us/library/aa970268%28v=vs.110%29.aspx...

Then again, are you going to accept the answer formally? So far, you accepted your own "answer" instead. Do you understand that it will be considered as abuse? Not only you posted your non-answer as "solution", you even marked it as "accepted". Please remove it, if you want other members to take you seriously...

—SA

I just read your fake "answer".

I'm close to make a conclusion that writing any answers for you would be totally useless, you don't hear anything. I clearly told you 1) there are no forms in WPF; 2) no parent-child forms or windows.

And even after that, you are asking about "parent and child form with one ribbon menu control" again. Listen, to get, you need to read and write in human language.

—SA