[external function declaration]
  FUNCTION ulong CreateMutexA(ulong lpMutexAttributes, boolean bInitialOwner, REF string lpszName) &
    LIBRARY "kernel32.dll"
  FUNCTION long GetLastError() LIBRARY "kernel32.dll"

  [powerscript]
  constant ulong ERROR_ALREADY_EXISTS = 183
  constant ulong SUCCESSFUL_EXECUTION = 0
  ulong lul_mutex
  ulong lpsa
  ulong lul_last_error
  boolean lb_ret = FALSE

  IF NOT (Handle(GetApplication()) = 0) THEN
     lul_mutex = CreateMutexA(lpsa, FALSE, as_appname)
     lul_last_error = GetLastError()
     lb_ret = NOT (lul_last_error = SUCCESSFUL_EXECUTION)
  END IF

  RETURN lb_ret