Hello Campbell,

Thank you for contacting Infragistics Developer Support.

I have been investigating into the behavior you are seeing in this case, and it does appear that you are correct that the UltraCalendarCombo does not have a Button / DropDownButton Appearance property.

I have been discussing this with our development teams, and the recommendations to style the UltraCalendarCombo’s drop-down button is to either use AppStylist for this and create an .isl with the button styling you are looking for, or use a DrawFilter to modify the color. The following draw filter can help you with this:

    public class UltraCalendarComboDrawFilter : IUIElementDrawFilter
    {
        public bool DrawElement(DrawPhase drawPhase, ref UIElementDrawParams drawParams)
        {
            CalendarDropDownButtonUIElement elem = drawParams.Element as CalendarDropDownButtonUIElement;                        
            drawParams.AppearanceData.BackColor = Color.Blue;                        
            return false;
        }

        public DrawPhase GetPhasesToFilter(ref UIElementDrawParams drawParams)
        {
            if(drawParams.Element is CalendarDropDownButtonUIElement)
            {
                return DrawPhase.BeforeDrawBackColor;
            }
            else
            {
                return DrawPhase.None;
            }
        }
    }

Please let me know if you have any other questions or concerns on this matter.

Perfect, thank you.