rem: return this._content.childNodes.item(this._getColumnCount() - 1); 
add: var cnt = this._getColumnCount() - 1; return cnt < 0 ? null : this._content.childNodes.item(cnt); 
context:     _lastColumn: function() {        return this._content.childNodes.item(this._getColumnCount() - 1);    },
meta: 5515	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/5515/f92e9b34465915b5a9427afe1d7d625eccda8376/GridBox.js/clean/src/thinwire/render/web/resources/GridBox.js