WPF: How can you add a new menuitem to a menu at runtime?

Question

I have a simple WPF application with a menu. I need to add menu items dynamically at runtime. When I simply create a new menu item, and add it onto its parent MenuItem, it does not display in the menu, regardless of if UpdateLayout is called.

What must happen to allow a menu to have additional items dynamically added at runtime?

Note: the following code doesn't work.

            MenuItem mi = new MenuItem();
            mi.Header = "Item to add";
            mi.Visibility = Visibility.Visible;
            //addTest is a menuitem that exists in the forms defined menu
            addTest.Items.Add(mi);
            addTest.UpdateLayout();

At the moment, the default menu items are defined in the xaml file. I want to add additional menu items onto this menu and its existing menu items. However, as stated, the above code does nothing.

Answer 1

//Add to main menu
MenuItem newMenuItem1 = new MenuItem();
newMenuItem1.Header = "Test 123";
this.MainMenu.Items.Add(newMenuItem1);

//Add to a sub item
MenuItem newMenuItem2 = new MenuItem();
MenuItem newExistMenuItem = (MenuItem)this.MainMenu.Items[0];
newMenuItem2.Header = "Test 456";
newExistMenuItem.Items.Add(newMenuItem2);