GetNextProcess
You use the GetNextProcess to get the process serial number of the next process
PSN is a pointer to a valid process serial number returned from
noErr (0) No error
paramErr (-50) Process serial number is invalid
procNotFound (-600) No process in the process list following the specified
process
Notes: You can use the returned process serial number from this function in
number to specify a target application when your application sends a
high-level event.