As I know, signal events don't have logical condition assigned to it. If you want throw a signal event in some conditions, use other artifacts before the incoming connections.
You can use a rule for that.. and let the rule signal de event when it's needed. leverate the power of the rule engine
Thanks for your replies. Although I can see the 2 options I remember Kris mentioning that you can define conditions for incoming events (at the time there was no editor support and the only way to do it was editing the XML). I tried editing the XML however the signal node changes in appearence and then it requires an incoming connection.