Fixed GtkToolPalette realize() vfunc.

It seems with latest GSEAL work for widget->window access a
call to gtk_widget_set_window() was missed (added the window
assignment and now the palette shows up in Glade again).

gtk/gtktoolpalette.c

@@ -683,6 +683,7 @@ gtk_tool_palette_realize (GtkWidget *widget)
 
   window = gdk_window_new (gtk_widget_get_parent_window (widget),
                            &attributes, attributes_mask);
+  gtk_widget_set_window (widget, window);
   gdk_window_set_user_data (window, widget);
 
   gtk_widget_style_attach (widget);