rem: var selection = this._tree.view.selection; 
add: var selection = this._tree.view.selection; 
context:     onSelectionChanged: function()    {        var selection = this._tree.view.selection;         this._removeButton.disabled = (selection.count != 1);        this._changeButton.disabled = (selection.count != 1);    },
meta: 7450	/local1/tlutelli/issta_data/temp/all_js/javascript/2007_temp/2007/7450/e1d42ad3fad63b72826a4e2ed0726866484c9ac3/editors.js/buggy/extension/content/firebug/editors.js