unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  Menus, ComCtrls;

type
  TForm1 = class(TForm)
    PageControl1: TPageControl;
    TabSheet1: TTabSheet;
    TabSheet2: TTabSheet;
    TabSheet3: TTabSheet;
    TabSheet4: TTabSheet;
    PopupMenu1: TPopupMenu;
    pmTabSheet: TMenuItem;
    procedure PageControl1ContextPopup(Sender: TObject; MousePos: TPoint;
      var Handled: Boolean);
  private
    { Private-Deklarationen }
    function InRect(X,Y : Integer; R : TRect): Boolean;
    function GetTabSheet(PageControl : TPageControl; Position : TPoint) : TTabSheet;
  public
    { Public-Deklarationen }
  end;

var
  Form1: TForm1;

implementation

{$R *.DFM}

function TForm1.GetTabSheet(PageControl: TPageControl; Position: TPoint): TTabSheet;
var
  iCnt : Integer;
begin
  Result:=Nil;
  For iCnt:=0 to PageControl.PageCount-1 do
    begin
    If InRect(Position.X,Position.Y,PageControl.TabRect(iCnt)) then
      begin
      Result:=PageControl.Pages[iCnt];
      Exit;
      end;
    end;
end;

function TForm1.InRect(X, Y: Integer; R: TRect): Boolean;
begin
  result := (X >= R.Left) and (X <= R.Right) and
            (Y >= R.Top) and (Y <= R.Bottom);
end;

procedure TForm1.PageControl1ContextPopup(Sender: TObject; MousePos: TPoint; var Handled: Boolean);
var
  TabSheet : TTabSheet;
begin
  TabSheet:=GetTabSheet(PageControl1,MousePos);
  If TabSheet<>Nil then // Nur <> Nil wenn im TabRect geklickt wurde !!!
    pmTabSheet.Caption:=TabSheet.Caption
    else
      pmTabSheet.Caption:=PageControl1.ActivePage.Caption

end;

end.