Citação:
  Private Function ValidarTudo(ByRef Tela As Control, ByVal controlefoco As Control) As Boolean

        t_errovalidacao = False

        Dim Campo As Object

        Dim allTextBoxes = From txt In Tela.Controls
                           Order By txt.TabIndex


        For Each Campo In allTextBoxes

            If TypeOf Campo Is System.Windows.Forms.GroupBox Or
                TypeOf Campo Is System.Windows.Forms.TabPage Or
                TypeOf Campo Is System.Windows.Forms.Panel Then

                ValidarTudo(Campo, controlefoco)

            ElseIf TypeOf Campo Is System.Windows.Forms.TextBox Or
                   TypeOf Campo Is System.Windows.Forms.ComboBox Or
                   TypeOf Campo Is System.Windows.Forms.CheckBox Then

                Campo.Focus()
                controlefoco.Focus()

                If t_errovalidacao = True Then
                    Exit For
                End If

            End If

        Next

        If t_errovalidacao = True Then

            Return True

        Else

            Return False

        End If

    End Function

Citação:
  Private Sub W_PAIS_Validating(sender As System.Object, e As System.ComponentModel.CancelEventArgs) Handles W_PAIS.Validating

        If IsNumeric(W_PAIS.Text) = False Then

            MessageBox.Show([Ô]Codigo do pais invalido![Ô], [Ô]Aviso[Ô], MessageBoxButtons.OK, MessageBoxIcon.Information)
            t_errovalidacao = True
            e.Cancel = True

        Else

            If CInt(W_PAIS.Text) <= 0 Then

                MessageBox.Show([Ô]Codigo do pais invalido![Ô], [Ô]Aviso[Ô], MessageBoxButtons.OK, MessageBoxIcon.Information)
                t_errovalidacao = True
                e.Cancel = True

            End If

        End If

    End Sub