Hi, [Warning: Long post! TL;DR: Ctrl + ASCII character below 0x3F generally don't seem to work as default binding. The post also contains a bunch of working suggestions, partially from what similar programs use, including where they clash with Emacs or shell keybindings. :-]
On Tue, Apr 23, 2013 at 03:43:09PM +0100, Joe Corneli wrote: > And yet, the default binding conflicts with the default binding C-a > for `move-beginning-of-line' in Emacs, which presumably affects many > users. Rather than have lots of different workarounds > (http://emacswiki.org/emacs/GnuScreen#toc1), might it make sense to > change the default binding? Per user, yes, but not generally. Screen's C-a is hardwired in too many people's finger muscles. Oh, and I'm a happy Screen and Emacs user and still use C-a. I don't mind pressing C-a a to get to the beginning of the line if my Emacs runs inside Screen. (Yes, occassionally I have a leading "a" in non-screen Emacsen. ;-) > (One of the users on the Emacs Wiki page suggests C-; but notes no > luck with experiments trying to bind it.) I thought I got it once working like this (with screen 4.0.3) once: escape '^;;' But I can't reproduce it anymore and it now always argues "Two characters are required with -e option, not '^;;'." The same happens for any character below ASCII 0x3F (which is "?"): None of the special characters +, -, *, ", #, %, &, !, ', (, ), ., / or , work with Control as Screen default binding. Neither do digits. It seems as if Screen doesn't make a difference between C-; and ;, too. Because if I say escape ;; both, C-; and ; seem to have the same behaviour. I suspect this is the case because the classic "control" sequences are basically typed as Control key plus the character at ASCII Byte value | 0x40 (i.e. bitwised or'ed with 64; adding works in that case, too), so 0x0A (line feed) is C-j (try to press C-j in Emacs and see what it does), because J is 0x4A. So I suspect the only characters which can be used with control in text mode are those above 0x40, i.e. @, (captial) A-Z and [, \, ], ^, _, `, etc. The only exception I found so far was the question mark (0x3F). While escape ^>> (">" = 0x3E) does throw the common error message as mentioned above, the command escape ^?? doesn't and seems to work. Strange. I'm confused. Anyway, about choosing a usable default binding itself: Keynav, a keyboard-based way to move the X cursor uses C-;, too. (But that's X and hence something completely different. ;-) And I haven't noticed that I triggered keynav accidentially, so this keybinding doesn't seem to be used by any Emacs feature I used and hence would make indeed an promising default binding. But then on the other hand, I have keyboards where I only have a left Ctrl key, so I'd have to type C-; with two hands (at least on US keyboard layouts), which would likely bother me. C-', C-., C-, and C-. would fall in the same catgory, but don't work either for the same reasons -- same error message. Additionally, C-/ is already bound to undo in Emacs (works even in text mode, why?), but since undo in Emacs has multiple keybindings, at least C-_ and C-x u come to my mind, this should be an issue. But let's go to _working_ solutions for the default binding: C-o is also an suggestion on http://emacswiki.org/emacs/GnuScreen#toc1 It's bound to open-line in Emacs, but I never use that. Nevertheless, it would also a two-handed command on some laptops. Ratpoison, an X window manager which is modeled after Screen uses C-t -- which is "transpose-chars" (i.e. switch the two characters around the text cursor) in Emacs. I don't mind pressing C-t t there. (Also suggested on http://emacswiki.org/emacs/GnuScreen#toc1) Tmux, a Screen work-alike, uses C-b -- which is backward-char in Emacs. (I would mind to have to press any key twice to just go one character left.) Byobu, a wrapper and configuration system for Screen and Tmux uses function keys (F1 to F12) for managing windows and tries to not use a prefix-based scheme where possible. Mosh, a remote shell with some of Screen's capabilities uses C-^, but is only needed seldomly there (in comparison to Screen) and it would bother me to have to press Shift in addition to Ctrl. And I would likely type the "6" key with my right hand, i.e. another two-handed keystroke. A friend of mine used backtick ("`", without modifier). Not sure how he passed a backtick to the program inside Screen then. I'd rather propose C-`, but that's unpleasant to type on some laptop keyboards where the ` key is more to the left than the Ctrl key. Another friend of mine, who uses nested Screen sessions, uses C-a on the outer screen and C-z on the inner screen. C-z is needed in most shells to suspend a program, so you'll have at least a collision there. (That's the only situation where I would change Screen's default binding. Always having to calculate and count how many C-a you have to type in a row to reach which nesting level of Screen is tedious and error-prone. So my conclusion on that topic is: There are many ways to do it and it depends a lot on the programs you acutally use inside the Screen session. Having to type C-a a to go to the beginning of the line in emacs or the shell isn't that bad. :-) You very likely won't find a better keybinding which suits everyone, mostly due to _no_ keybinding is perfect and C-a is too well-known. HTH. Kind regards, Axel -- /~\ Plain Text Ribbon Campaign | Axel Beckert \ / Say No to HTML in E-Mail and News | a...@deuxchevaux.org (Mail) X See http://www.asciiribbon.org/ | a...@noone.org (Mail+Jabber) / \ I love long mails: http://email.is-not-s.ms/ | http://noone.org/abe/ (Web) _______________________________________________ screen-users mailing list screen-users@gnu.org https://lists.gnu.org/mailman/listinfo/screen-users
