DSANDLER  The free alternatives have a number of limitations. Standalone apps must be started manually; they don't work unless you remember to use them. Java applets can't draw over the entire screen, and a great deal of image persistence on Macs occurs in areas a web-based tool can't touch (e.g. the menu bar and Dock). Finally, I'm not aware of any other software that uses high-contrast moving patterns like the ones pioneered by LCD Scrub, which, in my own personal experience, have worked where other techniques and tools did not.   
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