+// there can potentially be one message box per thread so we use a hash map
+// with thread ids as keys and (currently shown) message boxes as values
+//
+// TODO: replace this with wxTLS once it's available
+WX_DECLARE_HASH_MAP(unsigned long, wxMessageDialog *,
+ wxIntegerHash, wxIntegerEqual,
+ wxMessageDialogMap);
+
+namespace
+{
+
+wxMessageDialogMap& HookMap()
+{
+ static wxMessageDialogMap s_Map;
+
+ return s_Map;
+}
+
+} // anonymous namespace
+
+/* static */
+WXLRESULT wxCALLBACK
+wxMessageDialog::HookFunction(int code, WXWPARAM wParam, WXLPARAM lParam)
+{
+ // Find the thread-local instance of wxMessageDialog
+ const DWORD tid = ::GetCurrentThreadId();
+ wxMessageDialogMap::iterator node = HookMap().find(tid);
+ wxCHECK_MSG( node != HookMap().end(), false,
+ wxT("bogus thread id in wxMessageDialog::Hook") );
+
+ wxMessageDialog * const wnd = node->second;
+
+ const HHOOK hhook = (HHOOK)wnd->m_hook;
+ const LRESULT rc = ::CallNextHookEx(hhook, code, wParam, lParam);
+
+ if ( code == HC_ACTION && lParam )
+ {
+ const CWPRETSTRUCT * const s = (CWPRETSTRUCT *)lParam;
+
+ if ( s->message == HCBT_ACTIVATE )
+ {
+ // we won't need this hook any longer
+ ::UnhookWindowsHookEx(hhook);
+ wnd->m_hook = NULL;
+ HookMap().erase(tid);
+
+ if ( wnd->GetMessageDialogStyle() & wxCENTER )
+ {
+ wnd->SetHWND(s->hwnd);
+ wnd->Center(); // center on parent
+ wnd->SetHWND(NULL);
+ }
+ //else: default behaviour, center on screen
+ }
+ }
+
+ return rc;
+}
+