The first issue is related to different key binding support due either to OS differences or Tk version differences.
Yeah, that is really a downer, currently, that I could not use '_' in key binding. I will look into that some more, no doubt. Quite possibly that would have to do Tk installed here. I found a patch while searching for reason|solution for Tk dieing with sig 11 when compiled with Xft, which may or may not fix the this key binding issue.
Anyway, please do ignore the change in __DATA__ related to underline key binding line. I should not have included that in the patch posted earlier.