added wxDialog::GetParentForModalDialog() and use it to try to always create modal dialogs with a parent (slightly modified patch 1702962)

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@45588 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/generic/propdlg.cpp

@@ -62,6 +62,8 @@ bool wxPropertySheetDialog::Create(wxWindow* parent, wxWindowID id, const wxStri
                                        const wxPoint& pos, const wxSize& sz, long style,
                                        const wxString& name)
 {
+    parent = GetParentForModalDialog(parent);
+
     if (!wxDialog::Create(parent, id, title, pos, sz, style|wxCLIP_CHILDREN, name))
         return false;