It appears so. At 800x600 full screen there's no horizontal scrollbar but it's there at 800x600 according to Sizer; when you set the window to 800x600 in Sizer with the desktop at 800x600, the window doesn't go full screen. Rather, it goes to the edges of the screen such that IE's borders still show. The few pixels that the borders take up are what're causing the anomoly.
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