#340 Crash if TDialog::Create fails in debug mode

[Vidar Hasfjord]

In debug mode, with __WARN defined, the WARNX statement in TDialog::Create will crash when GetHandle returns 0, which it does in case of dialog creation failure:

:::C++
  WARNX(OwlWin, !GetHandle(), 0, _T("CreateDialog[Indirect]Param failed: ") <<
    _T("Class: \"") << tstring(GetClassName()).c_str() << _T("\", ") <<
    _T("Title: \"") << tstring(Title).c_str() << _T("\", ") <<
    _T("Parent: ") << (Parent ? static_cast<void*>(Parent->GetHandle()) : 0) << _T(", ") <<
    _T("Module: \"") << GetModule()->GetModuleFileName());

The reason is that TDialog::GetClassName does not return a valid string pointer, causing the tstring constructor to fail. TDialog::GetClassName returns WC_DIALOG, which is defined as MAKEINTATOM(0x8002). This value is an atom table key disguised as an string pointer. See About Atom Tables at MSDN. In short, the return value from GetClassName can not generally be used as a string pointer, as it is here.