How do I properly apply padding to a group box control? - vb.net

Question

I have a class that inherits a panel which I am adding a group box to. This group box contains for now a couple text boxes. I would like to have the text boxes centered horizontally and vertically within the group box by using the AutoSize property of the group box and the Padding property of the group box. Here is my attempt:
Imports System.Drawing
Public Class pnlItemMstr_A_OSI
Inherits Panel
Public Sub New(ByRef ItemMstr_DS As DataSet, ByVal padding As Integer)
MyBase.New()
Dim drItemMstr As DataRow = ItemMstr_DS.Tables(0)(0)
Dim txtHeight As Integer = 26
' article numbers
Dim grpArtNum As New GroupBox
Dim txtARTC_NUM_DOM_C As New TextBox
Dim txtARTC_NUM_CAN_C As New TextBox
With txtARTC_NUM_DOM_C
.Text = drItemMstr("ARTC_NUM_DOM_C").ToString
.Size = New Size(200, txtHeight)
.Location = New Point(0, 0)
End With
With txtARTC_NUM_CAN_C
.Text = drItemMstr("ARTC_NUM_CAN_C").ToString
.Size = New Size(200, txtHeight)
.Location = New Point(0, txtHeight)
End With
With grpArtNum
grpArtNum.Text = "Article Number"
grpArtNum.Padding = New Padding(padding)
grpArtNum.Controls.Add(txtARTC_NUM_DOM_C)
grpArtNum.Controls.Add(txtARTC_NUM_CAN_C)
End With
Me.Controls.Add(grpArtNum)
End Sub
End Class
What I am ending up with is ugly and not what I would expect to happen, notice how the group box text is cut off:
It seems the padding is not being applied properly, but I am sure I am just doing something wrong.

Answer 1

The Padding property is used primarily for Dock Styled child controls, so try adding a dock filled panel into your GroupBox to contain those TextBoxes:
With grpArtNum
grpArtNum.Text = "Article Number"
grpArtNum.Padding = New Padding(padding)
Dim innerPanel As New Panel With {.Dock = DockStyle.Fill}
innerPanel.Controls.Add(txtARTC_NUM_DOM_C)
innerPanel.Controls.Add(txtARTC_NUM_CAN_C)
grpArtNum.Controls.Add(innerPanel)
End With