'宣言
Protected Overridable Function OnBeforeDisplayToolTip( _
ByVal ultraControl As Infragistics.Win.IUltraControl, _
ByVal element As Infragistics.Win.UIElement, _
ByRef toolTipInfo As Infragistics.Win.ToolTipInfo, _
ByVal trigger As ControlUIElementBase.ToolTipTrigger _
) As Boolean