PaintBox в FormsABC. Как с ним работать?

uses FormsABC;
 
//если добавить это - можно убрать везде System.Drawing.
//то есть, к примеру, вместо System.Drawing.Color.Green писать Color.Green
//uses System.Drawing;
 
begin
  var pb := new PaintBox;
  pb.Width := MainForm.Width;
  pb.Height := MainForm.Height;
  
  var gr := pb.Graphics;
  
  //Для контуров
  var Pen := new System.Drawing.Pen(System.Drawing.Color.Red);
  
  //Для закрашивания
  var Brush := new System.Drawing.SolidBrush(System.Drawing.Color.Green);
  
  gr.FillEllipse(Brush, 20,20,100,50);
  gr.DrawEllipse(Pen, 20,20,100,50);
  
  Pen.Color := System.Drawing.Color.Blue;
  gr.DrawEllipse(Pen, 20,70,100,50);
  
end.

uses FormsABC;
 
var 
  clockOut:PaintBox;
  clockSize:integer:=500;
  pen:System.Drawing.Pen;
 
procedure Init;
begin
  MainForm.Title := 'Clock & Timer & Stopwatch';
  MainForm.SetSize(clockSize+30,clockSize+50);
  MainForm.CenterOnScreen;
  
  var Pen := new System.Drawing.Pen(System.Drawing.Color.Red);
  
  clockOut:=new PaintBox();
  clockOut.Height:=clockSize;
  clockOut.Width:=clockSize;
end;
 
procedure Draw;
var size:integer;
begin
  Pen.Color:=Color.Black;
  
  with clockOut do
    begin
    Graphics.Clear(Color.White);
    Graphics.DrawEllipse(Pen,0,0,30,30);
    end;
end;
 
 
begin
  Init;
  Draw;
end.

uses FormsABC;
 
var 
  clockOut:PaintBox;
  clockSize:integer:=500;
  Pen := new System.Drawing.Pen(System.Drawing.Color.Black);
procedure Init;
begin
  MainForm.Title := 'Clock & Timer & Stopwatch';
  MainForm.SetSize(clockSize+30,clockSize+50);
  MainForm.CenterOnScreen;
  
  var Pen := new System.Drawing.Pen(System.Drawing.Color.Red);
  
  clockOut := new PaintBox();
  clockOut.Height := clockSize;
  clockOut.Width := clockSize;
end;
 
procedure Draw;
var size:integer;
begin
  Pen.Color:=System.Drawing.Color.Black;
  
  with clockOut do
    begin
    Graphics.Clear(Color.White);
    Graphics.DrawEllipse(Pen,0,0,30,30);
    end;
end;
 
 
begin
  Init;
  Draw;
end.