> The general idea is that "letterboxing" will mask the window's real dimensions by keeping the window width and height at multiples of 200px and 100px during the resize operation --generating the same window dimensions for all users-- and then adding a "gray space" at the top, bottom, left, or right of the current page.

> The advertising code, which listens to window resize events, then reads the generic dimensions, sends the data to its server, and only after does Firefox remove the "gray spaces" using a smooth animation a few milliseconds later.

Would using a setTimeout() on the window resize event bypass this? Send the data 20-50ms after resize is completed giving enough time for the letterboxing stuff to go away revealing the actual dimensions, or something? They say it only blocks the dimensions during the resize event and FF removes the letterboxing "a few ms later"