mintty and Control-` , Control-~

Thomas Wolff towo@towo.net
Sat Apr 20 22:52:00 GMT 2013


Am 20.04.2013 22:14, schrieb Andy Koppe:
> On 21 March 2013 15:53, Ryan Johnson wrote:
>> On 21/03/2013 11:30 AM, Igor Bukanov wrote:
>>> It seems that mintty in Cygwin under Windows-7 does not pass C-`
>>> (Control-backtick, in US keyboard this is the key above the tab) nor
>>> C-~ (or Control-Shift-backtick) to terminal applications. Any reason
>>> for that?
>> A quick test [3] in shortcut override mode [1] suggests that mintty never
>> receives that key combination in the first place.
> Nah, it does receive it alright. Well, for me anyay. Shortcut override
> mode only affects combinations that mintty normally uses for its own
> purposes, for example Shift+Insert for paste.
>
>> However, trying the same test in xterm, I get \000 and \036 for C-` and C-~,
>> respectively. Neither of those seems to be correct [2] (\000 is ^@ and \036
>> is ^^)
> Indeed. Backtick and tilde don't directly correspond to control
> characters, so mintty doesn't send anything for them.
>
> What you can do is enable the so-called modifyOtherKeys mode (which
> comes from xterm), in which case mintty sends the keycodes specified
> on the following page for combinations that don't have a standard
> keycode:
>
> http://www.leonerd.org.uk/hacks/fixterms/
>
> The following will enable modifyOtherKeys mode level 1:
>
> $ echo -ne '\e[>4;1m'
>
> There's also a level 2, in which those special keycodes are sent even
> for standard combinations such as Ctrl+letter.
>
> $ echo -ne '\e[>4;2m'
>
>> but it's still odd that xterm can receive key codes that mintty misses.
> I guess I decided not to support those keycodes for Ctrl+` and Ctrl+~
> because they're not intuitive and they just send the same as Ctrl+@
> and Ctrl+^ (and also Ctrl+Space and Ctrl+Enter) anyway.
>
> In order to make them useful without enabling modifyOtherKeys mode,
> how about if Ctrl combinations with backtick (ASCII 0x60), opening and
> closing brace (0x7B and 0x7D), pipe (0x7C), and tilde (0x7E) were
> mapped to C1 control characters (in the U+0080 to U+009E range).
I don't think it's useful to support C1 control characters because 
virtually nobody will ever want to input them via keyboard;
even more if only a random subset of C1 can be supported this is only 
confusing.

> Incidentally, on US and UK keyboards (and others) that's what already
> happens for the braces and pipe symbol, because for example the pipe
> symbol is typed with Shift+\, and mintty maps Ctrl+Shift+\ to U+009C
> as explained at http://code.google.com/p/mintty/wiki/Keycodes#Ctrl.
I would drop those, too.

> I hope I've suitably confused matters now.
Yes :)
Thomas

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