in js/drill.js [111:118]
setCurrentDoc : function() {
var current_l2 = $("li.toctree-l2.current");
var current_l3 = $("li.toctree-l3.current");
Drill.Docs._setPlusMinus(current_l2);
Drill.Docs._setPlusMinus( current_l3.parent().prev("li") ); // requires knowledge of html structure...bad...bad.
// alternatively, set these up in the rendering of the docs, like the current_section and current are done.
},