The following example demonstrates creating a descendant of the TTrackbar component that overrides the CreateParams method, and clears the TBS_ENABLESELRANGE flag from the params style. This results in a Trackbar component that has a small thin track for the slider to move upon. Note that the TBS_ENABLESELRANGE constant is declared in the CommCtrl unit. Example:

uses CommCtrl, ComCtrls;
type TMyTrackBar = class(TTrackBar)
  procedure CreateParams(var Params: TCreateParams); override;
end;
procedure TMyTrackBar.CreateParams(var Params: TCreateParams);
begin
  inherited;
  Params.Style := Params.Style and not TBS_ENABLESELRANGE;
end;
var
  MyTrackbar : TMyTrackbar;
procedure TForm .Button Click(Sender: TObject);
begin
  MyTrackBar := TMyTrackbar.Create(Form );
  MyTrackbar.Parent := Form ;
  MyTrackbar.Left :=  00;
  MyTrackbar.Top :=  00;
  MyTrackbar.Width :=  50;
  MyTrackbar.Height := 45;
  MyTrackBar.Visible := true;
end;