procedure TStatusBar1.WMPaint(var Message: TWMPaint);
var
a:TTime;
begin
self.Panels.Items[2].Text:='Текущее время: '+TimeToStr(Time);
inherited;
a:=Now+StrToTime('00:00:01');
while TimeToStr(a)<>TimeToStr(Now) do
 Application.ProcessMessages;
SendMessage(self.Handle,WM_Paint,0,0);
end;

StatusBar1.Panels.Items[2].Text:='Текущее время: '+TimeToStr(Time);

unit Unit1;
interface
uses
 Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
 Dialogs, ComCtrls, ExtCtrls, StdCtrls;

type
 TMyStatusBar = class(TStatusBar)
 private
   FTimer: TTimer;
   procedure UpdateTime(Sender: TObject);
   procedure SetActive(const Value: Boolean);
   function GetActive: Boolean;
 protected
   procedure Resize; override;
 public
   constructor Create(AOwner: TComponent); override;
   destructor Destroy; override;
 published
   property Active: Boolean read GetActive write SetActive;
 end;

 TForm1 = class(TForm)
   CheckBox1: TCheckBox;
   procedure FormCreate(Sender: TObject);
   procedure CheckBox1Click(Sender: TObject);
 private
   StB: TMyStatusBar;
   { Private declarations }
 public
   { Public declarations }
 end;

var
 Form1: TForm1;

implementation

{$R *.dfm}

{ TMyStatusBar }

constructor TMyStatusBar.Create(AOwner: TComponent);
begin
 inherited;
 FTimer:=TTimer.Create(self);
 FTimer.OnTimer:=UpdateTime;
 Panels.Add;
 Panels.Add;
end;

destructor TMyStatusBar.Destroy;
begin
 FTimer.Free;
 inherited;
end;

function TMyStatusBar.GetActive: Boolean;
begin
 Result:=FTimer.Enabled;
end;

procedure TMyStatusBar.Resize;
begin
 Panels[0].Width:=Width-100;
 inherited;
end;

procedure TMyStatusBar.SetActive(const Value: Boolean);
begin
 FTimer.Enabled := Value;
end;

procedure TMyStatusBar.UpdateTime(Sender: TObject);
begin
 Panels[1].Text:=TimeToStr(Time);
end;

//-----------------------------------------------------
procedure TForm1.FormCreate(Sender: TObject);
begin
 StB:=TMyStatusBar.Create(Self);
 StB.Parent:=Self;
 StB.Active:=True;
end;

procedure TForm1.CheckBox1Click(Sender: TObject);
begin
 StB.Active:=CheckBox1.Checked;
end;

end.

procedure TForm_Main.WndProc(var Message: TMessage);
begin
  // Все это делается согласно ошибке http://qc.codegear.com/wc/qcmain.aspx?d=58092
  with Message do
  begin
     case Msg of
        WM_DRAWITEM:
        begin
           with PDrawItemStruct(Message.LParam)^ do
              if (CtlType = ODT_MENU) and Assigned(Menu) and
                 (hwndItem = fStatusBarPro.Handle)
              then
                 CtlType := ODT_STATIC;
        end;
     end;
  end;
  inherited WndProc(Message);
end;