[css-ui-4] none value for nav-up, nav-right, nav-down, nav-left properties

[jihyerish]

It would be nice to add none value for disabling the directional navigation.

The directional focus navigation properties, nav-up, nav-right, nav-down, nav-left can be used for the responsive grid layout.
In this case, the specified directional navigation needs to be changed, or be disabled.

For example, here is a grid layout like this in a wide screen:

and it will change in the mobile as:

#content is specified as:

#content {
  nav-right: #menu;
  nav-up: #header;
  nav-down: #footer;
}
 
@media only screen and (max-width: 750px) {
  #content {
    nav-up: #menu;
    nav-down: #footer;
  }
}

But, in the mobile, it won't have the focus navigation to the right.
If #menu is given to nav-right, it may be an unintentional navigation.
The directional focus navigation would be changed to disable the right-side focus navigation:

#content {
  nav-right: #menu;
  nav-up: #header;
  nav-down: #footer;
}
 
@media only screen and (max-width: 750px) {
  #content {
    nav-right: none;
    nav-up: #menu;
    nav-down: #footer;
  }
}

[frivoal]

In this example, I would expect that setting nav-right to auto would be enough: there is nothing to the right, so the UA's heuristics should deal with that inteligently.

It seems that an explicit none would be needed for a different case: there is something focusable to the right, but you don't want the focus to go there if the user navigates right.

However, isn't that fairly use hostile? a mouse user would be able to focus/click on that element, but a keyboard user would either be unable to, or would have to discover a different path through the page.

This problem isn't new, since nav-*can already make some elements inaccessible if the author isn't careful and create navigation paths that avoid them, but the risk of the none value seems larger than its benefit to me.

[jihyerish]

This problem isn't new, since nav-*can already make some elements inaccessible if the author isn't careful and create navigation paths that avoid them, but the risk of the none value seems larger than its benefit to me.

Yes, you're right. none value causes some unreachable problems for the navigation.
As you said, the example above can be solved another way. : )