Use the SelForeColor and SelBackColor properties to define the foreground and  background colors of the selected date. Use the Background(exDropDownSelForeColor) property to specify the foreground color of the drop down portion of the control.

The following VB sample changes the selection colors for label and drop down part of the control:

With CalendarCombo1
	.SelBackColor = RGB(255,0,0)
	.SelForeColor = RGB(255,255,255)
	.Background(exDropDownSelBackColor) = .SelBackColor
	.Background(exDropDownSelForeColor) = .SelForeColor
End With

The following VB.NET sample changes the selection colors for label and drop down part of the control ( assembly version ):

With Excalendarcombo1
	.SelBackColor = Color.FromArgb(255,0,0)
	.SelForeColor = Color.FromArgb(255,255,255)
	.set_Background(exontrol.EXCALENDARLib.BackgroundPartEnum.exDropDownSelBackColor,.SelBackColor)
	.set_Background(exontrol.EXCALENDARLib.BackgroundPartEnum.exDropDownSelForeColor,.SelForeColor)
End With

The following C# sample changes the selection colors for label and drop down part of the control ( assembly version ):

excalendarcombo1.SelBackColor = Color.FromArgb(255,0,0);
excalendarcombo1.SelForeColor = Color.FromArgb(255,255,255);
excalendarcombo1.set_Background(exontrol.EXCALENDARLib.BackgroundPartEnum.exDropDownSelBackColor,excalendarcombo1.SelBackColor);
excalendarcombo1.set_Background(exontrol.EXCALENDARLib.BackgroundPartEnum.exDropDownSelForeColor,excalendarcombo1.SelForeColor);