avoid deprecated functions and direct struct access

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@67326 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/gtk/frame.cpp

@@ -332,7 +332,7 @@ void wxFrame::SetToolBar(wxToolBar *toolbar)
         {
             // Vertical toolbar and m_wxwindow go into an hbox, inside the
             // vbox (m_mainWidget). hbox is created on demand.
-            GtkWidget* hbox = m_wxwindow->parent;
+            GtkWidget* hbox = gtk_widget_get_parent(m_wxwindow);
             if (!GTK_IS_HBOX(hbox))
             {
                 hbox = gtk_hbox_new(false, 0);