Why doesn't the screen display fully on the voting page?

Unfortunately this is a bug with Facebook's code. Here is the bug report: http://bugs.developers.facebook.net/show_bug.cg i?id=10889

We are not sure when Facebook will have a fix for this. Until then, please ask the users who experience this problem to try refreshing the page to load the complete page as this bug is intermittent [is not experienced by all].