A while ago, we announced that we would be making a change to the canvas page to prevent applications from displaying information in the Facebook chrome, outside the canvas portion of the page. The fix involves wrapping the content of the canvas page inside the style attribute position:relative.
This change may impact your application and cause items to be displayed incorrectly in the following cases:
If you think that your application may be affected, please read the migration doc on the wiki to find out how you can test your canvas pages and make them work with the fix.
We will be flipping the switch to wrap canvas pages in position:relative in two weeks, on December 6th, 2007.