This feature cannot work reliably for reasons explained in lp:1463505. Remove
the option on OS X builds and force cursor to the small one.
https://bugs.launchpad.net/kicad/+bug/1463505
> Bernhard Stegmaier (stegmaier) wrote on 2016-01-14:
>
> As far as I see from the code this is no bug but done on intention.
>
> The reason probably is that on OSX in the legacy canvas you don't have the
> XOR-drawing as on other platforms. To the best of my knowledge, this would
> mean that on every mouse move you would have to repaint the whole window just
> to get rid of the "old" cross.
>
> So, I would say this is a clear "won't fix".
> We could think of just removing/disabling the button in the legacy canvas.
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