rem: return sourceIndex != -1 && sourceIndex != targetIndex && (orientation == Ci.nsITreeView.DROP_BEFORE || orientation == Ci.nsITreeView.DROP_AFTER);  
add: return (sourceIndex != -1 && sourceIndex != targetIndex && sourceIndex != (targetIndex + orientation)); 
context:   canDrop: function(targetIndex, orientation) {    var sourceIndex = this.getSourceIndexFromDrag();    return sourceIndex != -1 &&           sourceIndex != targetIndex &&            (orientation == Ci.nsITreeView.DROP_BEFORE ||            orientation == Ci.nsITreeView.DROP_AFTER);             },
meta: 5459	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/5459/468e598194a69728eda5a52f47f1bceb825feeb2/engineManager.js/buggy/browser/components/search/content/engineManager.js