[Boost-users] [statechart] - delay of handlinmg a specific event?

Hello, Is it possible to delay the handling of an event? If I've three states X, Y and Z; initial state is X. State Y is entered if X receives event y1. State Z is entered if X receives event z1. X is entered if Y receives event y2. Y is entered if Z receives event z2. If Y is entered then it executes a function which will generate event y2 during ist processing (function will be executed in another thread - thread passes event y2 to state machine). It is possible that event z1 is passed to the state machine before event y2. How can I delay processing of event z1 until y2 event handling has taken place? Regards, Oliver