Public Class Form1
 
	Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As _
  System.EventArgs) Handles Button1.Click
		Dim O As Object = New Test(Of X, Button)
		Dim T As ITest(Of Object, Windows.Forms.Control) = DirectCast(O, ITest(Of _
  Object, Windows.Forms.Control))
	End Sub
End Class
 
Public Interface ITest(Of TA, TB As Windows.Forms.Control)
 
End Interface
 
Public Class Test(Of TA, TB As Windows.Forms.Control)
	Implements ITest(Of TA, TB)
 
End Class
 
Public Class X
 
End Class