Don't get the string when the combobox returned CB_ERR when getting

the length.


git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@16826 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/msw/choice.cpp

@@ -202,7 +202,7 @@ wxString wxChoice::GetString(int n) const
 {
     size_t len = (size_t)::SendMessage(GetHwnd(), CB_GETLBTEXTLEN, n, 0);
     wxString str;
-    if (len) {
+    if (len != CB_ERR && len > 0) {
         if ( ::SendMessage(GetHwnd(), CB_GETLBTEXT, n,
                            (LPARAM)str.GetWriteBuf(len)) == CB_ERR ) {
             wxLogLastError(wxT("SendMessage(CB_GETLBTEXT)"));