procedure TSourceNotebook.NotebookMouseUp(Sender: TObject;
  Button: TMouseButton; Shift: TShiftState; X, Y: Integer);
var
  TabIndex: Integer;
begin
  if (Button = mbRight) then
  begin
    TabIndex:=FNotebook.IndexOfPageAt(X, smallint(Y));
    if TabIndex>=0 then
    begin
      TabPopUpMenu.PopupComponent := FNotebook;
      TabPopUpMenu.PopUp;
      TabPopUpMenu.PopupComponent := nil;
    end;
  end;
end;