[silverlight]

تقريبا البديل لك ف الدوت نت هو استخدام شئ مثل هذا

كود :

Public Function GetTextBox(ByVal sender As Control, ByVal Index As Integer) As TextBox
        Return (From Control In sender.Controls.Cast(Of Control)() Where _
                    TypeOf Control Is TextBox AndAlso _
                    Control.Tag IsNot Nothing AndAlso _
                    Control.Tag.ToString = Index.ToString _
                Select CType(Control, TextBox)).FirstOrDefault

   End Function