Внести изменения в программу рисования

uses GraphABC;
var i: array[1..80] of integer;
j: array[1..20] of integer;
 
procedure MouseDown(x,y,mb: integer);
begin
rectangle(1,1,20,20);
floodfill(2,2,clblack);
rectangle(21,1,40,20);
floodfill(22,2,clyellow);
rectangle(41,1,60,20);
floodfill(42,2,clred);
rectangle(61,1,80,20);
floodfill(62,2,clgreen);
  MoveTo(x,y);
  for var i:=1 to 20 do
  if x=i then 
  for var j:=1 to 20 do
  if y=j then
  setpencolor(clblack);
  for var i:=21 to 40 do
  if x=i then 
  for var j:=1 to 20 do
  if y=j then
  setpencolor(clyellow);
  for var i:=41 to 60 do
  if x=i then
  for var j:=1 to 20 do
  if y=j then
  setpencolor(clred);
  for var i:=61 to 80 do
  if x=i then 
  for var j:=1 to 20 do
  if y=j then
  setpencolor(clgreen);
end;
 
procedure MouseMove(x,y,mb: integer);
begin
  if mb=1 then LineTo(x,y);
end;
 
begin
  OnMouseDown := MouseDown;
  OnMouseMove := MouseMove
end.

uses GraphABC;
 
const
  colors : array of Color = (clBlack, clYellow, clRed, clGreen);
  clrBox = 20;
 
procedure DrawRects;
begin
  Pen.Color := clDarkGray;
  for var n := 0 to colors.Count-1 do
    begin
      Brush.Color := colors[n];
      Rectangle(1+n*clrBox, 1, clrBox+n*clrBox, clrBox);
    end;
end;
 
var Draw := False;
 
procedure MouseDown(x,y,mb: integer);
begin
  for var n := 0 to colors.Count-1 do
    if (x > 1+n*clrBox) and (x < clrBox+n*clrBox) and
       (y > 1) and (y < clrBox) then Pen.Color := colors[n];
  MoveTo(x,y);
end;
 
procedure MouseMove(x,y,mb: integer);
begin
  if mb=1 then LineTo(x,y);
end;
 
begin
  OnMouseDown := MouseDown;
  OnMouseMove := MouseMove;
  DrawRects;
end.