libview: use GtkObject where it has to be in GTK+2 build

fix build warnings caused by some mistakes made in 3de4956ee7

libview/ev-view-presentation.c

@@ -1179,7 +1179,11 @@ ev_view_presentation_key_press_event (GtkWidget   *widget,
 	EvViewPresentation *pview = EV_VIEW_PRESENTATION (widget);
 
 	if (pview->state == EV_PRESENTATION_END)
+#if GTK_CHECK_VERSION (3, 0, 0)
 		return gtk_bindings_activate_event (G_OBJECT (widget), event);
+#else
+		return gtk_bindings_activate_event (GTK_OBJECT (widget), event);
+#endif
 
 	switch (event->keyval) {
 	case GDK_KEY_b:
@@ -1239,7 +1243,11 @@ ev_view_presentation_key_press_event (GtkWidget   *widget,
 		return TRUE;
 	}
 
+#if GTK_CHECK_VERSION (3, 0, 0)
 	return gtk_bindings_activate_event (G_OBJECT (widget), event);
+#else
+	return gtk_bindings_activate_event (GTK_OBJECT (widget), event);
+#endif
 }
 
 static gboolean

libview/ev-view.c

@@ -4427,7 +4427,11 @@ ev_view_key_press_event (GtkWidget   *widget,
 		return FALSE;
 	}
 
+#if GTK_CHECK_VERSION (3, 0, 0)
 	return gtk_bindings_activate_event (G_OBJECT (widget), event);
+#else
+	return gtk_bindings_activate_event (GTK_OBJECT (widget), event);
+#endif
 }
 
 static gint

shell/main.c

@@ -234,6 +234,10 @@ main (int argc, char *argv[])
 	textdomain (GETTEXT_PACKAGE);
 #endif
 
+#if GTK_CHECK_VERSION (3, 0, 0)
+	gdk_set_allowed_backends ("x11");
+#endif
+
 	context = g_option_context_new (N_("MATE Document Viewer"));
 	g_option_context_set_translation_domain(context, GETTEXT_PACKAGE);
 	g_option_context_add_main_entries (context, goption_options, GETTEXT_PACKAGE);