keyboard input in terminal emulators vs X11 apps

[Ernest Adrogué <nfdisco@gmail.com>]

Hi,

I was setting some key bindings in emacs and it puzzled me
that some of those bindings worked in emacs-x but not in emacs-nox.

Then I fired up emacs in a tty, in an X terminal emulator and also a
graphical frame and quoted-insert several key combinations that seem
problematic. This is the result

|           | del   | backspace | C-backspace | C-M-space        |
|-----------+-------+-----------+-------------+------------------|
| linux tty | ^[[3~ | ^?        | ^H          | ^[               |
| xfce term | ^[[3~ | ^?        | ^?          | ^[  (^[ + space) |
| gtk emacs | ^D    | ^?        |             | \200             |

(I wasn't able to quote-insert C-backspace in gtk emacs, it simply
killed the word before the point.)

By looking at the table above it can be seen that the xfce terminal
emulator generates a wrong escape sequence when C-backspace is
pressed, which is the same sequence as backspace. (This explains why
this binding didn't work when emacs was running in a terminal
emulator.) The C-M-space sequence is also suspect because it doesn't
match that of the linux tty. Is this a bug in the terminal emulator or
a X.org thing? I don't know.

Also, it appears that gtk emacs sometimes gets completely different
escape sequences, this I don't understand either.

Any comment on this issue will be appreciated.

Cheers,
Ernest