There is a MDI parent RadForm containing a RadMenu with items. There is a MDI child RadForm which also contains a RadMenu with items. The mnemonics are enabled for all the menu items. The menu merging is disabled (RadMenu.AllowMerge=false).

When you show the parent form together with the child form and focus the child form, pressing the Alt key highlights only the menu items from the parent form. It is not possible to activate the menu items from the child form.

Please refer to the attached sample project and gif file illustrating the obtained incorrect behavior and the observed behavior with a standard MS Form and MenuStrip

We can create a Scrollable menu panel with buttons at the top and bottom to move the items. A similar functionality is already implemented in WPF:

The default MS ContextMenuStrip shows tooltips for disabled menu items: