From this Multiple Screen tutorial:
http://www.scirra.com/tutorials/73/supporting-multiple-screen-sizes/page-2
I think it should be mentioned in the tutorial, when you use:
Unbounded scrolling: No -> the game canvas always appear on top-left corner
Unbounded scrolling: Yes -> the game canvas appear in the middle of window (which usually what most people want)
I spend my whole afternoon trying to figure out how to center my canvas in Full Screen Mode <img src="smileys/smiley5.gif" border="0" align="middle"> (because the default Unbounded scrolling is set to No).
btw is this intended to work this way ?