Re: KEYNAV: Buttons (bug 53577) and Accessibility

["Padraig O'Briain" <Padraig Obriain Sun COM>]

I have looked more depply at behavior requested by Calumn and do not think 
these changes are urgent for accessibility. My comments are below.

Padraig


A toggle, check or radio button should not be activated if keyboard focus
is given to it by using a mnemonic that is shared by another control in the
same context.  In this case, keyboard focus should be given to that button,
at which point:

- pressing Spacebar should activate the button;

- pressing the same mnemonic again should cycles focus to the next control
in the context that shares the same mnemonic;

- pressing Enter should activate the window's default button if it has one,
otherwise does nothing.

<POB> This deals with the case where two controls have the same mnemonic.
Can we regard this as a corner case and therefore of lower priority? </POB>

When any button within a functional group of mutually exclusive toggle or
radio buttons has focus:

- pressing Tab should move focus to the control immediately after the last
button in that group;

- pressing Shift+Tab should move focus to the control immediately before
the first button in that group;

<POB> My understanding is that only a group of radio buttons are mutually
exclusive so this would not apply to toggle buttons. A radio group does
not have any layout connotations so the concept of the first and last buttons
in the group are not meaningful. Normally the radio buttons would be in a
box so that they appear close together on the screen but I do not think that 
there is anything which forces all the buttons to be in the same box. Perhaps
we could assume that the radio buttons are in the same box and interpret
this as requiring Tab to move to the first control after the container of
a radio button if the radio button is in a radio button group. This may be
tricky to implement as the container will need to be able to determine 
whether it contains a radio button group. </POB>


When any button within a functional group of check buttons has focus:

- pressing Tab should move focus to the next button in that group, or to
the control immediately after the last button in that group if it is the
last button that is currently focused.

- pressing Shift+Tab should move focus to the previous button in that
group, or to the control immediately before the first button in that group
if it is the first button that is currently focused.

<POB> This works but cycles around. </POB>.

When any button within a functional group of toggle, check or radio buttons
has focus (mutually exclusive or not):

- pressing the up or left arrow should move focus to the previous enabled
button in the group, wrapping around to the last button in the group if
necessary;

- pressing the down or right arrow should move focus to the next enabled
button in the group, wrapping around to the first button in the group if
necessary.

<POB> I think that the behavior of the up and down arrows are as required.
When runnning testgtk and choosing radio buttons option I found that the
behavior of the right and left arrows very strange. There were four radio
buttons, button1, button2, button3 and inconsistent. No matter which button
had focus left arrow changed focus to button3 and right arrow changed focus
to button2. </POB>

<POB> The behavior of the up, down, left and right arrows is to move to the
adjacent control in the direction implied by the arrow. The behavior of the 
left and right arrows described above looks like a bug. I have logged bug
60690 for this.</POB>

[Check http://developer.gnome.org/projects/gap/keyboardnav.html for any
 later proposals that may not have filtered through to this bug report yet]