C # embed the MDI window into a normal window

There is a kind of demand called Metamorphosis. This example: the customer's system uses a Framework library, that is, dynamically adding controls to a Main Window Based on the configuration, the program to be embedded is an MDI main window, and a colleague calls for help. what should I do? Abnormal! So I thought of the previous experiences of embedding my window into msdn help in the vc6 era and using the API to try it. So I spent a few minutes writing a test, taking a photo on my mobile phone and sending a MMS, and my colleagues worked hard, it is a solution. interestingly, the provider of the Framework was still working hard to assist in this embedded work, and we were excited when we saw our code. isn't it unreasonable? Don't forget, when C # is absent, we do everything like this.