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Re: mintty and modifier keys

On 19/07/2012 3:06 PM, Andy Koppe wrote:
On 19 July 2012 16:37, Ryan Johnson wrote:
Hi all (mostly Andy),

I notice that mintty 1.1 handles certain key combinations differently than

ctrl+enter produces 0x1e (RS) vs. CR in xterm
alt+enter produces ESC CR vs. nothing at all in xterm

ctrl+shift+<letter> emits the unicode C2 control codepoints (0xc281 through
0xc29a); xterm emits the C0 control value as if shift were unpressed.

So, two questions:
1. Is there a particular reason for this behavior?
Yes, I tried to make as many key combinations as reasonably possible
available to applications without having to enable a special mode. I
chose ^^ (0x1e) for Ctrl+Enter rather than a multi-character code so
as to be able to use it in stty settings. Similarly, Ctrl+Backspace
sends ^_ (0x1f).
... and then those get encoded with utf-8 as appropriate. Got it.

Perhaps rxvt or some other non-xterm terminal emulator does it?
Nope, they're mintty-specific.
Fair enough. They seem like reasonable choices, especially compared with xterm (where some key combos send nothing at all!)

2. Is there documentation somewhere of what convention mintty follows for
the various special cases?

See also this on how those keycodes could be put to use in the stty settings:
Nice. I didn't know that was there. How hard would it be for me to get ncurses to grok these codes?

(these questions are partly triggered by frustration at shift+enter not
working, which lead to me finding a reasonably sane proposal to fix these
kinds of terminal woes [1]; I was surprised to find that mintty can already
distinguish some key presses that xterm can't)

Hmm, that basically describes xterm's "modifyOtherKeys" mode, which
mintty supports too. This can be enabled with the sequence "\e[>4;1m".
(That's for level 1. There's also level 2, enabled with "\e[>4;2m",
where the suggested CSI u keycodes are sent even for Ctrl+letter
... except neither mode makes any visible difference in xterm-281-1: shift+enter and ctrl+enter both continue sending CR, and alt+enter still does nothing (level 1); ctrl+a still sends ^A. Mintty works as advertized on both counts, yet another reason to like mintty, I guess.


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