var 
  isdown: boolean = false; 
 
procedure TForm1.ProgressBar1MouseDown(Sender: TObject; 
  Button: TMouseButton; Shift: TShiftState; X, Y: Integer); 
begin 
  if Button = mbleft then begin 
    isdown := true; 
    releasecapture; 
    with TProgressbar(Sender) do begin 
      Cursor := crHSplit; 
      application.ProcessMessages; 
      setcapture(handle); 
    end; 
  end; 
end; 
 
procedure TForm1.ProgressBar1MouseMove(Sender: TObject; Shift: TShiftState; 
  X, Y: Integer); 
begin 
  with TProgressbar(Sender) do begin 
    if isdown then 
      Position := round(x * (ProgressBar1.Max - ProgressBar1.Min) / 
        ProgressBar1.ClientWidth + ProgressBar1.Min) 
    else Cursor := crDefault; 
  end; 
end; 
 
procedure TForm1.ProgressBar1MouseUp(Sender: TObject; Button: TMouseButton; 
  Shift: TShiftState; X, Y: Integer); 
begin 
  isdown := false; 
end;