SerialEvent() examplecode not working with Arduino Mega.

Using Arduino Programming Questions
4

The serialEvent() method is NOT a magic bullet. There is NOTHING that serialEvent() does that

if(SomeSerialInstance.available() > 0)
{
}

in loop() doesn't do.

From my understandig this codes "waits" until you send a message.

It does NOT.

When you send a message, the messages get saved, sended back and get cleared.

Saved, yes. Sent back, no. Cleared, no. By serialEvent() that is. The loop() function does some of that.