property ToolBar.PopupFlatAppearance as Boolean
Specifies whether the control shows a flat appearance for sub-menus.

TypeDescription
Boolean A Boolean expression that specifies whether the popup menu displays the flay/gray portion to the left.
By default, the PopupFlatAppearance property is True. Use the Popup FlatBackColor property to specify the background color of the left side of the popup. Use the PopupFlatImageWidth property to specify the width of the column that displays icons/images/check or radio buttons.