The difficulty is in being able to detect when exactly the browser's toolbars are displayed, which is what creates the insets.
This is a bug we're aware of and might be able to fix in a future release. I'm using xScope's Overlay tool, but whenever my browser's scroll bars are displayed the overlay's measurements are off.xScope is eight tools in one that will help any designer or developer do their job faster and produce more accurate results.* Applies to all purchases made on excluding Toolboxes, Tool Carts, Diagnostics, Welders, Shop Equipment and shipped items weighing more than 150 pounds Excludes all Gifts and Branded Apparel items except branded apparel size exchanges for exact items.
Truly the 'Cadillac' of magnification tools, this handy little pocket-size 30x microscope also includes an 8x pull-out telescope, a 9x magnifying hand lens, a clock, a whistle, a compass and a flashlight!
