KEYNAV: Buttons (bug 53577) and Accessibility

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

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> This does not work. </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 arraows are as required.
When runnning testgtk and chgoosing radio buttons option I found that the
hahavior 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 nd right arrow changed focus
to button2. </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]