im going to assume that hes using the 'screen' object, which is the whole screen, not the normally used portion above the taskbar. although he could hardcode it to just snap to the amount of pixels that a normal taskbar takes up, not everyone uses a normal taskbar, or in the normal location. ive never looked at it, but im sure theres some way to figure out the depth and location of the taskbar.

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beat me to it