XP Style Collapsible GroupBox

        
protected override void OnSizeChanged(EventArgs e)
{
   HandleResize();
}

.AutoSizeMode=Windows.Forms.AutosizeMode.GrowAndShrink

private Rectangle m_toggleRect = new Rectangle(8, 2, 11, 11);

private Rectangle m_toggleRect = new Rectangle(8, 1, 11, 11);

Rectangle bounds = new Rectangle(ClientRectangle.X, ClientRectangle.Y + 6, ClientRectangle.Width, ClientRectangle.Height - 6);
GroupBoxRenderer.DrawGroupBox(g, bounds, Enabled ? GroupBoxState.Normal : GroupBoxState.Disabled);
.
.
.

Rectangle bounds = new Rectangle(ClientRectangle.X, ClientRectangle.Y, ClientRectangle.Width, ClientRectangle.Height);
GroupBoxRenderer.DrawGroupBox(g, bounds, String.Format("    {0}", Text), this.Font, Enabled ? GroupBoxState.Normal : GroupBoxState.Disabled);

        public bool IsCollapsed
        {
            get { return m_collapsed; }
            set
            {
                ....
 
                foreach (Control c in Controls)
                    c.Visible = !value;
 
                Invalidate();
            }
        }

        public bool IsCollapsed
        {
            get { return m_collapsed; }
            set
            {
                ....
 
                //foreach (Control c in Controls)
                //    c.Visible = !value;

                // This will invalidate the groupbox OLNY, and the child controls will not redraw
                // This should also improve rendering speed
                Invalidate(false);
            }
        }

        void DrawToggleButton(Graphics g)
        {
            VisualStyleRenderer glyphRender = null;
            if (IsCollapsed)
                glyphRender = new VisualStyleRenderer(VisualStyleElement.TreeView.Glyph.Closed);
            else
                glyphRender = new VisualStyleRenderer(VisualStyleElement.TreeView.Glyph.Opened);
            glyphRender.DrawBackground(g, m_toggleRect);
        }

        void DrawToggleButton(Graphics g)
        {
            if (Application.RenderWithVisualStyles)
            {
                VisualStyleRenderer glyphRender = null;
                if (IsCollapsed)
                    glyphRender = new VisualStyleRenderer(VisualStyleElement.TreeView.Glyph.Closed);
                else
                    glyphRender = new VisualStyleRenderer(VisualStyleElement.TreeView.Glyph.Opened);
                glyphRender.DrawBackground(g, m_toggleRect);
            }
            else
            {
                if (IsCollapsed)
                    g.DrawImage(PlusImage, m_toggleRect);
                else
                    g.DrawImage(MinusImage, m_toggleRect);
            }
        }

void ResizeParent()
{
   int deltaHeight = this.FullHeight - m_collapsedHeight;
   this.ResizeParent(this.Parent, !this.Collapsed, deltaHeight);
}
 
void ResizeParent(Control control, bool collapsed, int deltaHeight)
{
   if (control != null)
   {
      this.ResizeParent(control.Parent, collapsed, deltaHeight);
 
      foreach (Control c in control.Controls)
      {
         if ((c.Anchor & AnchorStyles.Bottom) != 0)
            continue;
 
         Point p = c.Location;
         if (p.Y <= this.Location.Y)
            continue;
 
         if (collapsed)
            p.Y -= deltaHeight;
         else
            p.Y += deltaHeight;
         c.Location = p;                    
      }
 
      Size s = control.Size;
      if (collapsed)
         s.Height -= deltaHeight;
      else
         s.Height += deltaHeight;
      control.Size = s;
   }
}
</code>
 
void ToggleCollapsed()
{
   <code>this.ResizeParent();</code>
   this.Collapsed = !this.Collapsed;
   if (this.CollapseBoxClickedEvent != null)
      this.CollapseBoxClickedEvent(this);
}

Brush lBrush = new SolidBrush( BackColor );
g.FillRectangle( lBrush, i_textPos, bounds.Y, i_endPos - i_textPos, 2 );

SystemPens.FromSystemColor(Parent.BackColor)

    /// <summary>
    /// CollapsibleGroupBoxDesigner is an control designer for the that 
    /// CollapsibleGroupBox. Allows mouse clicks on the collapse button. 
    /// </summary>
    [System.Security.Permissions.PermissionSet(System.Security.Permissions.SecurityAction.Demand, Name = "FullTrust")]
    public class CollapsibleGroupBoxDesigner : System.Windows.Forms.Design.ParentControlDesigner
    {
        // This boolean state reflects whether the mouse is over the control.
        protected override  bool  GetHitTest(Point point)
        {
            CollapsibleGroupBox me = this.Control as CollapsibleGroupBox;
 
            if (me.m_toggleRect.Contains(me.PointToClient(point)))
            {
                // we can handle that; user clicked on toggle box.
                return true;
            }
            //Nope not interested
            return false;
        }
    }

    /// <summary>
    /// GroupBox control that provides functionality to 
    /// allow it to be collapsed.
    /// </summary>
    [ToolboxBitmap(typeof(CollapsibleGroupBox))]
    [DesignerAttribute(typeof(CollapsibleGroupBoxDesigner))]
    public partial class CollapsibleGroupBox : GroupBox
    {
 
        ....
        public Rectangle m_toggleRect = new Rectangle(8, 2, 11, 11); // not private
        ....
 
        /// <summary>
        /// Save the size if control is collapsed. VS will serialize the attribute for us. 
        /// It is also shown in properties.
        /// </summary>
        [DefaultValue(false), Browsable(true), DesignerSerializationVisibility(DesignerSerializationVisibility.Visible)]
        public Size FullSize
        {
            get
            {
                return m_FullSize;
            }
            set
            {
                m_FullSize = value;
            }
        }