Re: New key-binding system

[Owen Taylor <otaylor redhat com>]

Tom Tromey <tromey@cygnus.com> writes:

> I have a couple questions about the new key binding scheme.
> 
> Owen>   bind "<Control>c" { "cut-clipboard" () }
> 
> Can you have multi-key bindings?  E.g., to emulate Emacs I'd like to
> have all my apps map "C-x C-c" to "quit()".  Is this possible?

As of right now, it is not. It wouldn't be impossible to add
(and is present, for instance, in Tk, and I think also in Xt),
but my initial guess was that it was more trouble than it was
worth.

[ There are some slighlty sticky issues to worry about - on
  the matching side - for instance, we do have key-release bindings
  as well (or I think we decided to add them), so you need
  to make

  "<control>x;<control>c" 

  match a sequence like

  "<control>" "<control>x" "<release><control>" "<release>x" 
  "<control>" "<control>c"

  Which is the actual sequence of bindable events that 
  GTK+ will see ]
 
I suppose it would help with pseudo-vi bindings as well
as pseudo-emacs bindings, though. You could get things like
'dd' to work, though not 'y4w'.

As far as getting anything to map to quit(), I suppose the
way to do it would be:

 bind "xyz" { "activate-menu" ("File/Quit") }

> How is localization handled?  For instance, what will the default
> binding for the left arrow key be?  It either has to be different for
> l-to-r and r-to-l locales, or it has to have a strange -- physical and
> not logical -- functional mapping.  I suppose each right/left-motion
> action signal could have both a physical and a logical variant, so
> that both "C-f" and "right arrow" could be sensibly bound by default
> in a locale-independent way (this presumes that C-f would always be
> "logical forward").  This seems baroque, though.

Hmmm, I didn't think about that. I see to ways to handle it:

The gross, but functional hack:

 If the widget has the "mirror" flag set, then before matching
 any bindings for that widget, swap the Left and Right keysyms.

The complicated but "clean" solution:

 Add a mechanism for conditional keybindings to the setup
 so that different bindings for Left and Right can be specified
 for mirrored and non-mirrored widgets.

I think for widgets like Entry or Text where the logical
forward direction can change, the only thing to do is to
have separate physical and logical actions.

Regards,
                                        Owen