This can be accomplished if the main menu is placed onto a dock control, whose AllowDocking is set to False. Here are the step-by-step instructions of how to implement this feature in your application:
1. Drop the TdxBarDockControl component onto a form. The dock control is aligned to the top by default. Set the BarManager property to the BarManager of the form;
2. Dock the main menu to the dock control;
3. Set the AllowDocking to False of the dock control;
4. Set the NotDocking property of the main menu to [dsNone, dsLeft, dsTop, dsRight, dsBottom] (i.e. activate all options of the NotDocking).
The attached samples demonstrate the results of these steps.