Private _listTextBoxes As New List(Of TextBox)
    Private _listButtons As New List(Of Button)
 
    Private Sub GetControls(ByVal Container As Control)
        For Each c As Control In Container.Controls
            If TypeOf (c) Is TextBox Then
                If c.Name.StartsWith("TextBox") Or c.Name.StartsWith("TxtBez") _
                  Then
                    _listTextBoxes.Add(DirectCast(c, TextBox))
                End If
            ElseIf TypeOf (c) Is Button Then
                If c.Name.StartsWith("Btn_") Then
                    _listButtons.Add(DirectCast(c, Button))
                End If
            End If
        Next
    End Sub
 
 
    Private Sub SetVisiblity(ByVal visible As Boolean)
        For Each tB As TextBox In _listTextBoxes
            tB.Visible = visible
        Next
        For Each Btn As Button In _listButtons
            Btn.Visible = visible
        Next
    End Sub
 
    Private Sub TabControl1_SelectedIndexChanged(ByVal sender As System.Object, _
      ByVal e As System.EventArgs) Handles TabControl1.SelectedIndexChanged
        GetControls(GroupBox1)
        SetVisiblity(False)
    End Sub