How do I set an image for the application menu button
Set the Ribbon.ApplicationMenuButtonImage property.
http://help.infragistics.com/Help/NetAdvantage/NET/2007.3/CLR2.0/html/Infragistics2.Win.UltraWinToolbars.v7.3~Infragistics.Win.UltraWinToolbars.Ribbon~ApplicationMenuButtonImage.html