unit Unit1;

{$mode objfpc}{$H+}

interface

uses
  Classes, SysUtils, FileUtil, Forms, Controls, Graphics, Dialogs, ExtCtrls;

type

  { TForm1 }

  TForm1 = class(TForm)
    Panel1: TPanel;
    procedure Panel1MouseDown(Sender: TObject; Button: TMouseButton;
      Shift: TShiftState; X, Y: Integer);
    procedure Panel1MouseMove(Sender: TObject; Shift: TShiftState; X, Y: Integer
      );
    procedure Panel1MouseUp(Sender: TObject; Button: TMouseButton;
      Shift: TShiftState; X, Y: Integer);
  private
   fdx, fdy : Integer;
   fresize : boolean;
  public

  end;

var
  Form1: TForm1;

implementation

{$R *.lfm}

{ TForm1 }

procedure TForm1.Panel1MouseMove(Sender: TObject; Shift: TShiftState; X,
  Y: Integer);
begin

 if (GetCaptureControl = panel1) and fresize then
  panel1.SetBounds(panel1.left, panel1.top, x + fdx, y + fdy);

end;

procedure TForm1.Panel1MouseUp(Sender: TObject; Button: TMouseButton;
  Shift: TShiftState; X, Y: Integer);
begin
  panel1.cursor := crDefault;
end;

procedure TForm1.Panel1MouseDown(Sender: TObject; Button: TMouseButton;
  Shift: TShiftState; X, Y: Integer);
const

 sizeGripSize = 17;

begin

  fdx := panel1.width - x;
  fdy := panel1.height - y;

  fresize := (fdx < sizegripSize) and (fdy < sizeGripSize);

  if fresize then
   panel1.Cursor := crHandPoint;

end;

end.