Previously, for the following snippet, the menu's LnF was incorrectly
being forced to the default LnF. The correct behaviour is to display the
menu using LnF v4. The menu doesn't have an explicit LnF set, so it
should use the LnF of its parent component.

    LookAndFeel::setDefaultLookAndFeel (&lookAndFeel_V1);
    setLookAndFeel (&lookAndFeel_V4);
    PopupMenu().showMenuAsync (PopupMenu::Options{}.withParentComponent (this));