Public Class Form1
 
	Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As _
  System.EventArgs) Handles Button1.Click
		Dim Obj As Object = New ExtTest()
		Dim T As ITest(Of Object, Control) = DirectCast(Obj, ITest(Of Object, _
  Control))
	End Sub
End Class
 
 
 
#Region "Test1"
Public Interface ITest(Of TA, TB As Windows.Forms.Control)
 
	Property O As TA
	Property Ctrl As TB
 
End Interface
 
Public Class Test(Of TA, TB As Windows.Forms.Control)
	Implements ITest(Of TA, TB)
 
	Public Property Ctrl As TB Implements ITest(Of TA, TB).Ctrl
		Get
 
		End Get
		Set(ByVal value As TB)
 
		End Set
	End Property
 
	Public Property O As TA Implements ITest(Of TA, TB).O
		Get
 
		End Get
		Set(ByVal value As TA)
 
		End Set
	End Property
 
End Class
 
Public Class ExtTest
	Inherits Test(Of X, Button)
 
End Class
 
 
Public Class X
 
End Class
 
#End Region