Currently I’m writing NetFlow analyser as a Rich Internet Application. After long consideration and evaluation of available open-source technologies I have concluded that GWT will be the best shot in this case (now I’m not so sure any more, but this is another story). To make building nice user interface easier I have decided to equip user side CLASSPATH with GWT-Ext library. GWT-Ext reuses ExtJS and ExtJS needs some underlying JavaScript framework. A lot of people use YUI as base for ExtJS, so automatically I have started to use it too. And this is where the first problems arose.