A Boolean member variable that indicates whether the menu button appears pressed while the user makes a selection from the pop-up menu.
If the m_bStayPressed member is FALSE, the menu button does not become pressed when the uses clicks the button. In this case, the framework displays only the pop-up menu.
If the m_bStayPressed member is TRUE, the menu button becomes pressed when the user clicks the button. It stays pressed until after the user closes the pop-up menu, either by making a selection or canceling.