Re: [Evolution-hackers] Proposed Keyboard Navigation for Evolution Mail Reader and Calendar

[Calum Benson <calum benson sun com>]

On Wed, 2003-06-04 at 21:51, Anna Marie Dirks wrote:

> The HIG is not very specific about what key combinations might be
> quasi-preferable, if the Ctrl-based ones are taken.. Ctl+non-letters?
> Ctl+Alt+something? 

No, it's not, is it :)  Personally I'd say Ctrl+Alt+letters would be
preferable, then Ctrl+non-letters, since non-letters can cause problems
on various international keyboards.  (There's also the GIMP approach of
'no modifier at all', but I'd be loathe to recommend that and it
wouldn't really work in Evo anyway.)

> Calum: what is the perceived cost of using "Alt+letter" shortcuts,
> beyond the cautions indicated above? (They may conflict with WM
> shortcuts, and they may conflict with menu accelerators.) Specifically,
> is your main concern possible user confusion about the presence of a new
> modifier, or, is your main concern preventing possible menu conflicts?

Preventing conflicts is probably what I'd be more worried about. 
Shortcuts aren't generally localized (nor should they be), but menus and
menu items (and hence their mnemonics) obviously are.  So an Alt+letter
shortcut that works in one locale may cause problems in another, if a
menu or some other control is using it as a mnemonic as well.

(Using Alt for shortcuts potentially starts to break the user's mental
model of the difference between shortcuts and mnemonics somewhat too...
I don't know how big an issue that would be in reality, but since one is
localized and the other isn't, it might affect people who use the app in
more than one locale.)

BTW, at a bit of a tangent, I notice I suggested Ctrl+Arrowkeys/Home/End
rather than the proposed Alt+arrowkeys/Home/End for some functions.  In
fact Alt+arrowkeys/Home/End is probably OK-- I forgot we recommend them
in the HIG for Back, Forward, Up and Home, since they don't clash with
any default metacity shortcuts (and obviously can't clash with any
mnemonics).

> It would seem to me that pedantically sticking to the HIG's
> use-ctrl-keys edict, we're going to end up with some shortcuts that are
> unnecessarily difficult to remember and use. We're also going to have a
> huge headache whenever we try to add a new menuitem which requires a
> shortcut...

Well, Evo always strikes me as having too many shortcuts anyway, but I
guess you guys probably have the usability studies to prove me wrong :)

Just doing a really quick browse through the 1.2.4 menus, for example,
Ctrl-D for Edit->Delete seems pretty superfluous as Del also works (and
is the HIG recommendation).  Ctrl-Shift-B for 'Clear Search' also seems
a bit unnecessary, as there's a button right beside the text field
(making the menu item itself fairly redundant), and the button's label
could potentially have a mnemonic (provided it didn't clash with any
menu titles) which would provide the necessary quick keyboard access. 
Or if Ctrl-Shift-B is just the standard emacs shortcut for clearing text
or something, it should be part of the desktop-wide emacs keybinding
scheme and work in all text fields, rather than appearing as a special
menu item.

Maybe you've already looked at this sort of stuff for 1.4, I dunno... I
haven't had a Solaris build that runs yet :)

> On the other hand, we have very few (~7) single letters which are
> currently used in conjunction with the Alt key...and we add new
> top-level menus very infrequently. This makes the "Alt" key look like a
> seductive modifier to me...especially if there were a firm distinction
> between operations which use it and operations which don't. 

Yeah, I agree that using Alt for well-defined categories of shortcut
would certainly be more attractive than just starting to use it because
you'd run out of Ctrl shortcuts!  As I said, I think the main pitfall is
making sure it continues to work in all locales-- especially if these
are to be shortcuts that don't appear on menus, as I presume translators
won't necessarily know about them and may use them as mnemonics for
other things in the same context without realising.  

I know it's a tough call, and I'm glad I don't have to make it :)

Cheeri,
Calum.

-- 
CALUM BENSON, Usability Engineer       Sun Microsystems Ireland
mailto:calum benson sun com            GNOME Desktop Group
http://ie.sun.com                      +353 1 819 9771

Any opinions are personal and not necessarily those of Sun Microsystems