Problem with drawing and deleting rectangle

[Tomi]

Hello experts!

I would like draw a rectangle on images in my program with DrawFocusRect() function, but something is wrong, because I can't delete the rectangle from its previous place when I have more than one images.
These images are part of an own type:

Code: Pascal  [Select][+][-]

1. type Ttiles = class(TCustomimage)
2.   private
3.   public
4. end;

and a TScrollBox contains them (tilelist).
I load these images as a follows in a mouse event of a button:

Code: Pascal  [Select][+][-]

1. if (imageOpener.Execute) and (numbersourcetiles<255) then
2. begin
3.      sourcetileimg:=TPicture.Create;
4.      sourcetileimg.LoadFromFile(imageOpener.FileName);
5.      //
6.      setlength(tile,numbersourcetiles+1);
7.      tile[numbersourcetiles]:=Ttiles.Create(tilelist);
8.      tile[numbersourcetiles].Parent:=tilelist;
9.      tile[numbersourcetiles].OnMouseUp:=@srctileclick;
10.      tile[numbersourcetiles].OnPaint:=@tilePaint;
11.      if numbersourcetiles>0 then tile[numbersourcetiles].Top:=tile[numbersourcetiles-1].Top+tile[numbersourcetiles-1].height+2;
12.      tile[numbersourcetiles].width:=sourcetileimg.width;
13.      tile[numbersourcetiles].height:=sourcetileimg.height;
14.      tile[numbersourcetiles].canvas.copyrect(Rect(0,0,tile[numbersourcetiles].width,tile[numbersourcetiles].height),sourcetileimg.bitmap.canvas,Rect(0,0,sourcetileimg.width,sourcetileimg.height));
15.      inc(numbersourcetiles);
16.      freeandnil(sourcetileimg);
17. end;

This is the srctileclick function:

Code: Pascal  [Select][+][-]

1. procedure TForm1.srctileclick(Sender: TObject;
2.   Button: TMouseButton; Shift: TShiftState; X, Y: Integer);
3. var i: byte;
4. begin
5.   if numbersourcetiles>0 then
6.   begin
7.     for i:=0 to numbersourcetiles-1 do
8.     begin
9.          if (X>=tile[i].Left) and (X<=tile[i].Left+tile[i].width) and ((ScreenToClient(mouse.cursorpos).Y+tilelist.VertScrollBar.Position)-tilelist.Top>=tile[i].Top) and ((ScreenToClient(mouse.cursorpos).Y+tilelist.VertScrollBar.Position)-tilelist.Top<=tile[i].Top+tile[i].height) then
10.          begin
11.             if thereistiletoput=true then
12.             begin
13.                  FreeAndNil(tiletoput);
14.                  thereistiletoput:=false;
15.             end;
16.             if (GetKeyState(VK_CONTROL) and $80)<>0 then //Assign tile to grid:
17.             begin
18.                  X:=tile[i].ScreenToClient(mouse.cursorpos).X-(tile[i].ScreenToClient(mouse.cursorpos).X mod tilewidth);
19.                  Y:=tile[i].ScreenToClient(mouse.cursorpos).Y-(tile[i].ScreenToClient(mouse.cursorpos).Y mod tileheight);
20.             end;
21.             tilex:=X;
22.             tiley:=Y;
23.             tiletoput:=Tbitmap.Create;
24.             tiletoput.width:=tilewidth;
25.             tiletoput.height:=tileheight;
26.             tiletoput.canvas.copyrect(Rect(0,0,tilewidth,tileheight),tile[i].canvas,Rect(tilex,tiley,tilex+tilewidth,tiley+tileheight));
27.             thereistiletoput:=true;
28.             actualtileimage:=i;
29.             tile[actualtileimage].invalidate;
30.             Break;
31.          end;
32.     end;
33.   end;
34. end;

And the tilePaint function:

Code: Pascal  [Select][+][-]

1. procedure TForm1.tilePaint(Sender: TObject);
2. var fromx,fromy: word;
3. begin
4.   if thereistiletoput=true then
5.   begin
6.      if (GetKeyState(VK_CONTROL) and $80)<>0 then
7.      begin
8.          fromx:=tilex-(tilex mod tilewidth);
9.          fromy:=tiley-(tiley mod tileheight);
10.      end
11.      else
12.      begin
13.          fromx:=tilex;
14.          fromy:=tiley;
15.      end;
16.      tile[actualtileimage].canvas.drawfocusrect(Rect(fromx,fromy,fromx+tilewidth,fromy+tileheight));
17.   end;
18. end;

So, I would like put piece of images from an image onto the other's canvas and I would like make visual this piece for the user with this rectangle, but when I clicking the image, many rectangles remain on them.
What should I do? Is it possible to delete those unnecessary rectangles?