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Transfer functions are the only pointing facilitation technique actually used in modern graphical interfaces involving the indirect control of an on-screen cursor. But despite their general use, very little is known about them. We present EchoMouse, a device we created to characterize the transfer functions of any system, and libpointing, a toolkit that we developed to replicate and compare the ones used by Windows, OS X and Xorg. We describe these functions and report on an experiment that compared the default one of the three systems. Our results show that these default functions improve performance up to 24% compared to a unitless constant CD gain. We also found significant differences between them, with the one from OS X improving performance for small target widths but reducing its performance up to 9% for larger ones compared to Windows and Xorg. These results notably suggest replacing the constant …