为什么子程序不能同时实现接口和处理事件？

Sub MySub() Handles MyButton.Click Implements MyInterface.MyMethod
End Sub

Public MustInherit Class MyParentClass
    Protected WithEvents MyButton As Button

    Protected MustOverride Sub MySub() Handles MyButton.Click
End Class

Public Class MyDerivedClass : Inherits MyParentClass : Implements IMyInterface
    Protected Overrides Sub MySub() Implements IMyInterface.MyMethod
        \' Do something here...
    End Sub
End Class

Public Sub MySub(ByVal sender As System.Object, ByVal e As System.EventArgs)