gplt_x11 ignores SIGINT and SIGTSTP. Why?

[Dima K. <gn...@di...>]

Hi.

I'm looking at patching gplt_x11.c to work better with existing X window
IDs. This is coming along. In the process I'm discovering other things.
One is that for some reason the gnuplot x11 backend is explicitly
ignoring the SIGINT and SIGTSTP signals:

  https://github.com/gnuplot/gnuplot/blob/e9779f00507187653b8fb317f492833af5eaaa9a/src/gplt_x11.c#L5270

This results in zombie gplt_x11 processes. During normal operation
usually this doesn't happen, but I do periodically see gplt_x11 zombies.
While testing my new patches, I see these all the time, however. Does
anybody know why we're ignoring these signals? Version control says that
we were doing this from day 0 more or less.

Removing those two signal() calls doesn't obviously break anything, and
results in the zombie processes going away. Can/should we get rid of
those?

Thanks