The ON EVENT CALL command creates a local process which executes the procedure called by the command. The stack size used by this process is defined in the 4STK resource, ID 1. This process can be aborted, or will stop itself as soon as the ON EVENT CALL ("") command is used. You should never execute a new ON EVENT CALL process without closing the one currently in effect:

ON EVENT CALL ("EventMethod1")

ON EVENT CALL ("") `<< Finishes the current ON EVENT CALL

ON EVENT CALL ("EventMethod2")