Add missing tooltips on buttons of toolbars

UI/AdministrationUI/Toolbars/UIxAdministration.toolbar

@@ -1,6 +1,7 @@
 ( /* the toolbar groups -*-cperl-*- */
   ( { link = "#";
       label = "Help";
+      tooltip = "Help";
       onclick = "help(this);";
       image = "properties.png"; }
   )