You better do the NES Zelda way.Or, you know, you can make an illusion that the whole world is one layout, but actually it is lots of layouts. I think this will happen like this:
You are in Layout 1
When you go to the edge of it, you see the stuff from the next layout, but actually it is copied from the second layout.
When you go over the edge of Layout 1, the next Layout loads.And since the player saw no actual edge of the first layout, he will think it is a very big layout. Of course, you are going to <img src="smileys/smiley35.gif" border="0"> with global variables a lot.
Also, make sure you don't use free edition. If you don't know what is the worst thing about free edition, it has got a limit of events, up to just 100. And in games like Poke a Moan or Zeal Dah you will run out of events very quickly. That's what happened to me. I wanted to make a Zelda game along with a platformer and a space shooter, but I saw that events have a limit and said "<img src="smileys/smiley35.gif" border="0"> this. I am uploading the whole thing.".