make msg boxes without parent owned by top level app window

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@8511 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/msw/msgdlg.cpp

@@ -46,7 +46,8 @@ wxMessageDialog::wxMessageDialog(wxWindow *parent,
 
 int wxMessageDialog::ShowModal()
 {
-    if ( !wxTheApp->GetTopWindow() )
+    wxWindow *winTop = wxTheApp->GetTopWindow();
+    if ( !winTop )
     {
         // when the message box is shown from wxApp::OnInit() (i.e. before the
         // message loop is entered), this must be done or the next message box
@@ -56,8 +57,14 @@ int wxMessageDialog::ShowModal()
             wxTheApp->Dispatch();
     }
 
+    // use the top level window as parent if none specified
     HWND hWnd = 0;
-    if (m_parent) hWnd = (HWND) m_parent->GetHWND();
+    if ( m_parent )
+        hWnd = GetHwndOf(m_parent);
+    else if ( winTop )
+        hWnd = GetHwndOf(winTop);
+
+    // translate wx style in MSW
     unsigned int msStyle = MB_OK;
     if (m_dialogStyle & wxYES_NO)
     {
@@ -91,11 +98,15 @@ int wxMessageDialog::ShowModal()
     else
         msStyle |= MB_TASKMODAL;
 
-    int msAns = MessageBox(hWnd, (LPCTSTR)m_message.c_str(),
-                           (LPCTSTR)m_caption.c_str(), msStyle);
-    int ans = wxOK;
+    // do show the dialog
+    int msAns = MessageBox(hWnd, m_message.c_str(), m_caption.c_str(), msStyle);
+    int ans;
     switch (msAns)
     {
+        default:
+            wxFAIL_MSG(_T("unexpected ::MessageBox() return code"));
+            // fall through
+
         case IDCANCEL:
             ans = wxID_CANCEL;
             break;