1:
2:
3:
4:
5:
6:
7:
8:

Timer1Timer
begin
If Form1.Top<>(Screen.Height DIV 2)-(Form1.Height DIV 2)
Then Form1.Top:=(Screen.Height DIV 2)-(Form1.Height DIV2);

If Form1.Left<>(Screen.Width DIV 2)-(Form1.Widht DIV 2)
Then Form1.Left:=(Screen.Width DIV 2)-(Form1.Width DIV 2);
end;					

1:
2:
3:
4:
5:
6:
7:

procedure TForm2.FormCreate(Sender: TObject);
var
  hm: HMENU;
begin
  hm := GetSystemMenu(Handle, False);
  if (hm <> 0) then DeleteMenu(hm, SC_MOVE, MF_BYCOMMAND);
end;					

1:

 SetWindowPos()					

1:
2:
3:
4:
5:
6:
7:
8:
9:
10:
11:
12:
13:
14:
15:
16:
17:
18:
19:
20:

interface
  
uses
  ...

type
  TForm1 = class(TForm)
  ...
  private
    procedure WMMoving(var Msg: TWMMoving); message WM_MOVING;
  end;

...

implementation

procedure TForm1.WMMoving(var Msg: TWmMoving);
begin
  Msg.DragRect^ := BoundsRect;
end;