The functions are coded as follows:
{===========================================================================
  Notice that all the functions are used in an assignment
  operation to a variable called rgn. This is a
  private var that I declared for the form. The private var is
  accessible to all functions; I did this so that I could change the shape of
  the form or a control on the form, and use the same region.
===========================================================================}

procedure TForm1.DrawEllipticRegion(wnd : HWND; rect : TRect);
begin
  rgn := CreateEllipticRgn(rect.left, rect.top, rect.right, rect.bottom);
  SetWindowRgn(wnd, rgn, TRUE);
end;

procedure TForm1.DrawRndRectRegion(wnd : HWND; rect : TRect);
begin
  rgn := CreateRoundRectRgn(rect.left, rect.top, rect.right, rect.bottom, 30, 30);
  SetWindowRgn(wnd, rgn, TRUE);
end;

procedure TForm1.DrawPolygonRegion(wnd : HWND; rect : TRect; NumPoints : Integer; DoStarShape : Boolean);
const
  RadConvert = PI/180;
  Degrees    = 360;
  MaxLines   = 100;
var
  x, y,
  xCenter,
  yCenter,
  radius,
  pts,
  I       : Integer;
  angle,
  rotation: Extended;
  arPts   : Array[0..MaxLines] of TPoint;
begin

  xCenter := (rect.Right - rect.Left) div 2;
  yCenter := (rect.Bottom - rect.Top) div 2;
  if DoStarShape then
    begin
      rotation := Degrees/(2*NumPoints);
      pts := 2 * NumPoints;
    end
  else
    begin
      rotation := Degrees/NumPoints;             //get number of degrees to turn per point
      pts := NumPoints
    end;
  radius := yCenter;

{This loop defines the Cartesian points of the shape. Notice I''ve added 90 degrees to the rotation angle. This is so that shapes will stand up; otherwise they''ll lie on their sides. I had to brush up on my trigonometry to accomplish this (forgot all those sin and cos thingies). Many thanks to Terry Smithwick and David Ullrich for their assistance on CompuServe!}
  for I := 0 to pts - 1 do begin
    if DoStarShape then
      if (I mod 2) = 0 then //which means that
        radius := Round(radius/2)
      else
        radius := yCenter;

    angle := ((I * rotation) + 90) * RadConvert;
    x := xCenter + Round(cos(angle) * radius);
    y := yCente