Public Interface ITest(Of Out TA, Out TB As Windows.Forms.Control)
    ReadOnly Property O As TA
    ReadOnly Property Ctrl As TB
End Interface
 
Public Class Test(Of TA, TB As Windows.Forms.Control)
    Implements ITest(Of TA, TB)
    Private ReadOnly _Ctrl As TB
    Private ReadOnly _O As TA
 
    Public Sub New(O As TA, Ctrl As TB)
        Me._O = O
        Me._Ctrl = Ctrl
    End Sub
 
    Public ReadOnly Property Ctrl As TB Implements ITest(Of TA, TB).Ctrl
        Get
            Return _Ctrl
        End Get
    End Property
 
    Public ReadOnly Property O As TA Implements ITest(Of TA, TB).O
        Get
            Return _O
        End Get
    End Property
 
End Class

        Dim i1 As ITest(Of String, TextBox) = New Test(Of String, TextBox)( _
          "Test", New TextBox())
        Dim i2 As ITest(Of Object, Control) = i1