It's standard MDI behavior that the child's menu & toolbar items be merged with the parent's. Based on the screenshot provided, I'm not sure why you would even need MDI behavior anyways. Could you explain why you need it?
Currently using VS 2015 Enterprise on Win10 Enterprise x64.
No, it's not standard. I've tried it in a new project, where parents toolbar doesn't go over the MDI child. All the windows in the screenshot provided are in it's working stage. I just don't know what happened in this project, so the behavior is as shown.
I need a MDI behavior since it's a business application and many windows can be opened.