How to enable the expand or collapse behavior in the WinForms GroupBar?

Enable expand or collapse behavior

The GroupBar can be collapsed and expanded similar to the MS Outlook 2013 by handling the StateChanged in the GroupBar and SplitterDistance property in the SplitContainerAdv.

The following code example is to demonstrate the same.

//State Changed events occurred when Groupbar collapsed property changed
private void groupBar1_StateChanged(object sender, EventArgs e)
{
  //To change the splitter distance
    if (groupBar1.Size.Width > this.groupBar1.CollapsedWidth)
        this.splitContainer1.SplitterDistance = this.groupBar1.Width;
    else
        this.splitContainer1.SplitterDistance = groupBar1.Width;
}

'State Changed events occurred when Groupbar collapsed property changed
Private Sub groupBar1_StateChanged(ByVal sender As Object, ByVal e As EventArgs) Handles groupBar1.StateChanged
  'To change the splitter distance
    If groupBar1.Size.Width > Me.groupBar1.CollapsedWidth Then
        Me.splitContainer1.SplitterDistance = Me.groupBar1.Width
    Else
        Me.splitContainer1.SplitterDistance = groupBar1.Width
    End If
End Sub

Before Collapse

Show the items before collapse