Inserting submenus in an existing SDI menu

In the SDI app I am working on, I needed to be able to insert a new submenu
in the apps main menu based on the currently selected object. (My app uses
the nested splitter code found elsewhere on CodeGuru to provide multiple
views into a selected sound on an advanced MIDI soundcard). I found no
information on how to do it, so after a bit of trial and error I came up
with the technique shown in the following code. Please note that this code
is NOT directly reusable; but it should give you an idea of what needs to
be done. The submenus are all contained in a separate menubar,
IDR_OBJECT_MENUS; everything else should be clear to the experienced MFC
user :’)

// Add a an additional popup menu to the main menu which is 
// specific to the currently selected object type. If pViewClass is NULL,
// no menu is added.
void CMainFrame::AddViewMenu(CRuntimeClass* pViewClass)
{
	const int INSERT_POSITION = 3;
	const int DEFAULT_MENU_COUNT = 6; // INCOMPLETE - change when test menu is
	removed!
		enum { PROGRAM_MENU, LAYER_MENU, KEYMAP_MENU, SAMPLE_MENU };

	CMenu* pMenu = GetMenu();
	ASSERT(pMenu->GetMenuItemCount() == DEFAULT_MENU_COUNT
		|| pMenu->GetMenuItemCount() == DEFAULT_MENU_COUNT + 1);

	// If there is already an extra menu present, remove it
	if (pMenu->GetMenuItemCount() == DEFAULT_MENU_COUNT + 1)
		pMenu->RemoveMenu(INSERT_POSITION, MF_BYPOSITION);

	// Now based on the specific view type, add the appropriate menu
	int iMenuToAdd = -1;
	if (pViewClass == RUNTIME_CLASS(CProgramView))
		iMenuToAdd = PROGRAM_MENU;
	else if (pViewClass == RUNTIME_CLASS(CLayerView))
		iMenuToAdd = LAYER_MENU;
	else if (pViewClass != NULL)
		ASSERT(FALSE); // INCOMPLETE - other types!

	if (iMenuToAdd != -1)
	{
		// get the menu to add
		CMenu objectMenu;
		objectMenu.LoadMenu(IDR_OBJECT_MENUS);
		CMenu* pPopupMenu = objectMenu.GetSubMenu(iMenuToAdd);
		ASSERT(pPopupMenu != NULL);

		// get its string - *^&) Windows can't figure it out for itself
		CString strMenuItem;
		objectMenu.GetMenuString(iMenuToAdd, strMenuItem, MF_BYPOSITION);

		// Add it
		VERIFY(pMenu->InsertMenu(INSERT_POSITION, MF_BYPOSITION | MF_POPUP,
			(UINT)pPopupMenu->GetSafeHmenu(), strMenuItem));

		// remove from the other menu!
		objectMenu.RemoveMenu(iMenuToAdd, MF_BYPOSITION);
	}

	DrawMenuBar();
}

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