I think I understand what you're trying to do.
When you show a page from a microflow in Mendix, it won't automatically highlight a related menu item in the navigation menu. It will highlight that item if you click on it. You have a few options:
Have you taken a look at https://appstore.home.mendix.com/link/app/2964/First-Consulting/TabSwitcher in the app store. This might do what you want.
I'm not sure that what you're asking is really a tab container or a menu. If it is a menu, then just add an show page action to the end of your previous microflow to open the correct page.