To create the window region.

    private void CreateWindowRegion()

    {

      GraphicsPath gp=new GraphicsPath(FillMode.Winding);

      gp.AddArc(0,0,90,90,180,90);

      gp.AddLine(45,0,this.Size.Width-45,0);

      gp.AddArc(this.Size.Width-90,0,90,90,270,90);

      gp.AddLine(this.Size.Width,45,this.Size.Width,this.Size.Height-45);

      gp.AddArc(this.Size.Width-90,this.Size.Height-90,90,90,0,90);

      gp.AddLine(this.Size.Width-45,this.Size.Height,45,this.Size.Height);

      gp.AddArc(0,this.Size.Height-90,90,90,90,90);

      gp.AddLine(0,this.Size.Height-45,0,45);

      gp.CloseFigure();

      OuterPath=gp;

      GraphicsPath border=(GraphicsPath)gp.Clone();

      border.Widen(new Pen(Color.Black,4));

      borderRegion=new Region(border);

      System.Drawing.Region r = new Region(gp);

      r.Union(new Rectangle(this.Width-(45),45-closerPos,closerPos,closerPos));

      this.Region=r;    

    }

    Private Sub CreateWindowRegion()

      Dim gp As New GraphicsPath(FillMode.Winding)

      gp.AddArc(0, 0, 90, 90, 180, 90)

      gp.AddLine(45, 0, Me.Size.Width - 45, 0)

      gp.AddArc(Me.Size.Width - 90, 0, 90, 90, 270, 90)

      gp.AddLine(Me.Size.Width, 45, Me.Size.Width, Me.Size.Height - 45)

      gp.AddArc(Me.Size.Width - 90, Me.Size.Height - 90, 90, 90, 0, 90)

      gp.AddLine(Me.Size.Width - 45, Me.Size.Height, 45, Me.Size.Height)

      gp.AddArc(0, Me.Size.Height - 90, 90, 90, 90, 90)

      gp.AddLine(0, Me.Size.Height - 45, 0, 45)

      gp.CloseFigure()

      OuterPath = gp

      Dim border As GraphicsPath = CType(gp.Clone(), GraphicsPath)

      border.Widen(New Pen(Color.Black, 4))

      borderRegion = New [Region](border)

      Dim r = New [Region](gp)

      r.Union(New Rectangle(Me.Width - 45, 45 - closerPos, closerPos, closerPos))

      Me.Region = r

    End Sub 'CreateWindowRegion