The ApplicationMenuItemsPanel is a custom panel specifically designed to be used within the ControlTemplate of the ApplicationMenuPresenter and is used by the ApplicationMenu to display/host the items from its Items collection (in the left side of the ApplicationMenu). It's really not going to provide any help with trying to group items. I can't think of any easy way to accomplish what it sounds like you are looking for. You may want to submit a feature request and describe all the requirements you have. Perhaps one option is to add ToolMenuItem instances to the Items collection and then just retemplate these to look as if they are in the same group perhaps creating your own attached property so that all the items can change their background when the IsHighlighted of any one becomes true.