以下声明一个属性，当属性改变前后时候，触发事件，如果ICON为当前的ICON则不改变属性，也不触发事件。

 Public Property [Icon]() As Icon
            Get
                Return _icon
            End Get
            Set(ByVal Value As Icon)
                If Not (_icon Is Value) Then
                    OnPropertyChanging([Property].Icon)
                    _icon = Value
                    OnPropertyChanged([Property].Icon)
                End If
            End Set

以上用IS来判断可以
如果用EQUALS来判断呢？可没有

奇怪的是ICON本身没有EQUALS方法，当是它的CLONE却有EQUALS方法，查MSDN没有找到。.

Public Property Icon() As Icon
Get
Return _icon
End Get
Set(ByVal Value As Icon)
 If _icon Is Nothing Then 
                OnPropertyChanging([Property].Icon)
                _icon = Value
                OnPropertyChanged([Property].Icon)
                Return
            End If
If Not (_icon.Equals(Value)) Then
OnPropertyChanging([Property].Icon)
_icon = Value
OnPropertyChanged([Property].Icon)
End If
End Set
End Property
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