I've used Adblock plus in FF for a long time, and it works wonders. Waiting for them to update with a patch for these new WGT ads, lol.
Edit: Privoxy does indeed block the in-game WGT ads, but does not prevent the screen from adjusting size....
also, be warned - if you use the Privoxy solution for Chrome, it will disable Internet Explorer from reaching the internet. Just in case anyone still uses IE.......