you can override several methods of the generated editparts e.g. addNotify, handleNotificatione etc. You can also add listeners to your editparts. You should take a look at the package xxx.edit.parts. Of course you can also modify the generated commands and edit policies. Once you have found the right place to put your changes in you should think about using custom templates or GMF's extension points to place your code in. This way you do not loose code when deleting the generated and regenerate it again. This can sometime be quite handy.