Another complication. On Windows, this line doesn't do what it claims:
if (event.state & 12) != 0 and event.keysym == "Home":
# state&1==shift, state&4==control, state&8==alt
return # <Modifier-Home>; fall back to class binding
The comment says state&8==alt, but this is wrong. state&8==mod1, and on
Windows Tk defines mod1 to be num-lock. So if you have num-lock on,
home_callback will always fall back to the standard binding.
See the Tk source:
xlib/X11/X.h defines Mod1Mask
win/tkWinX.c maps VK_NUMLOCK to Mod1Mask