Gets or sets how a specific NavBar group is scrolled, using a scroll bar or scroll buttons.
A nullable ScrollMode value.
You can specify how navbar groups should be scrolled, via the attached ScrollingSettings.ScrollMode property, which is applicable to the NavBarControl.View object. The GroupScrollMode property allows you to override scroll mode for individual groups. If this property is set to null, a group's scroll mode is specified by the View's ScrollMode attached property. Otherwise, the group's scroll mode is specified by the GroupScrollMode property.