Blocking Clientside onChangeLevel(oldLevel, newLevel)
 

onChangeLevel(oldLevel, newLevel) would be called whenever you go through a level link, but the actual level change would not happen until this function returns.

This is critical for when you want to do something like disable weapons in the new level and you don't want that 0.05 second delay before it actually happens.

good idea

return false; (or true) Should prevent the level change from happening.

player.dontblock(); player.blockagain(); player.setshape();

Should work on client-side too.

you read my mind