'宣言
Public MustInherit Class UltraDropDownBase
Inherits UltraGridBase
Implements Infragistics.Shared.Serialization.ICodeDomSerializable, Infragistics.Win.AppStyling.ISupportAppStyling, Infragistics.Win.CalcEngine.IUltraCalcParticipant, Infragistics.Win.IDropDownResizeHandleOwner, Infragistics.Win.IFilterableValueList, Infragistics.Win.IProvideContentsVersion, Infragistics.Win.IProvideItemImageSize, Infragistics.Win.ISelectionManager, Infragistics.Win.ISupportPresets, Infragistics.Win.IUIElementProvider, Infragistics.Win.IUIElementTextProvider, Infragistics.Win.IUltraControl, Infragistics.Win.IUltraControlElement, Infragistics.Win.IValueList, Infragistics.Win.Touch.ISupportTouchMetrics, Infragistics.Win.UIAutomation.IProvideUIAutomation