Working on Portals, related questions

[xoft]

The hook is called whenever the client sends a PlayerMove packet. And I think the client moves the player all the time - if you switch on the debug screen (F3), you'll see that the coords keep changing even when the view seems to have stopped, in inrcrements of 0.000000001 etc. That might be the issue.

I'm not sure whether the server should be doing anything about that; I think your plugin should live with this - instead of checking for (non-)movement, why not check if the player has been inside the area for the specified amount of time?