fix running with GTK < 2.18 when built with later GTK

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_3_0_BRANCH@75760 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/gtk/private/gtk2-compat.h

@@ -298,6 +298,12 @@ static inline void wx_gtk_widget_set_allocation(GtkWidget* widget, const GtkAllo
 }
 #define gtk_widget_set_allocation wx_gtk_widget_set_allocation
 
+static inline gboolean wx_gtk_widget_is_toplevel(GtkWidget* widget)
+{
+    return GTK_WIDGET_TOPLEVEL(widget);
+}
+#define gtk_widget_is_toplevel wx_gtk_widget_is_toplevel
+
 // ----------------------------------------------------------------------------
 // the following were introduced in GTK+ 2.20
 

src/gtk/win_gtk.cpp

@@ -380,11 +380,7 @@ void wxPizza::put(GtkWidget* widget, int x, int y, int width, int height)
 {
     // Re-parenting a TLW under a child window is possible at wx level but
     // using a TLW as child at GTK+ level results in problems, so don't do it.
-#if GTK_CHECK_VERSION(2,19,3)
     if (!gtk_widget_is_toplevel(GTK_WIDGET(widget)))
-#else
-    if (!GTK_WIDGET_TOPLEVEL(GTK_WIDGET(widget)))
-#endif
         gtk_fixed_put(GTK_FIXED(this), widget, 0, 0);
 
     wxPizzaChild* child = new wxPizzaChild;