强类型泛型方法调用其参数的基类方法,而不是T?

MyForm 类,该类包含 Show() . 它还包含 CreateForm() 方法,它接受窗体的实例并调用阴影子:

Public Class MyForm
    Inherits Form

    Public Shadows Sub Show()
        MessageBox.Show("Shadowed implementation called!")
    End Sub
End Class

...

Public Sub CreateForm(ByVal childForm As MyForm)
    childForm.MdiParent = Me
    childForm.Show()
    childForm.Focus()
End Sub

CreateForm(New MyForm()) ,的阴影实现 显示() 正确调用。现在考虑以下通用实现:

Public Sub CreateForm(Of T As Form)(ByVal childForm As T)
    childForm.MdiParent = Me
    childForm.Show()
    childForm.Focus()
End Sub

CreateForm(Of MyForm)(New MyForm()) ,此强类型泛型方法从不调用阴影方法。