Neil's Place

October 5, 2009

Visible Focus Rings

Filed under: Uncategorized — enndeakin @ 3:59 pm

Platforms differ in the way that they show which element is focused. So does Firefox, which differs in a number of ways from platform conventions.

The typical way is to draw either a glow or dotted outline around a button or input field that accepts keyboard entry. However, this behaviour can sometimes cause unwanted visible display or bad interactions when the keyboard is not being used. For instance, when clicking a link on a page, the behaviour is to draw a visible dotted outline around the link, then load the next page. This is useful to know that the link has been clicked, but causes an unnecessary outline that can disrupt the appearance, especially if the link is an image or part of an image map.

One significant advantage of showing the link however, is that when going back to a page, one can immediately see where the keyboard focus is, and for non-keyboard use, indicates clearly which link was clicked, a useful indicator when visiting a series of links in succession.

Another behaviour is that, especially on Mac, various elements don’t switch the focus when clicking on them. For instance, clicking a checkbox in a dialog box or selecting from a dropdown list doesn’t change which element is focused. In this image, the first dropdown has a visible focus indicator (a blue glow around it), but clicking the later dropdown has not changed this.

On Windows, what used to be the norm is to show dotted outlines around focused elements, and show underlines under letters of the labels of controls or menus to indicate a key which can be used to focus or activate it. In today’s versions of Windows, though, that behaviour isn’t used, although it can be enabled through a system setting. Instead, these indicators are only visible once the user presses a key. For instance, pressing Alt shows the menu label indicators, as well as shows a visible focus ring around the element that accepts keyboard input. Tabbing to an element does similar.

The goal of bug 418521 is to improve the situations described above in Mozilla to be more compatible with how the system behaves. Followup bugs will address additional issues with specific controls. More specifically, this means:

On Windows, don’t show indicators at all until the user uses the keyboard to access an element. But, respect the system setting if the user wants them visible at all times.

On Mac, don’t focus elements when clicking on them, except for lists and text input fields.

On Linux, always show indicators. This is the current behaviour so Linux users won’t notice changes from this bug.

One change of note on all platforms is that links will no longer show the dotted focus outline when they are clicked, whether they are image links or otherwise. However, the dotted outline will be made visible when navigating back to the page, or when switching tabs back to that page. This solves the issue of not adding visible noise to the page in normal usage, but doesn’t prevent the user from seeing which link was clicked when going back to that page again.

For this change to be effective, a new css pseudoclass is proposed, to accompany the existing :focus pseudoclass.

The :focus pseudoclass will continue to work as it does now. If will match any element which is focused. However, the new pseudoclass :-moz-focusring will only match when the element is focused and the focus indicator should be shown. So if you are creating a theme for instance, the :-moz-focusring pseudoclass should be used to show focus indicators as this deals with all of the platform specific details. For example:


button:-moz-focusring {
  outline: 1px dotted black;
}

For details of the changes see comment 57 in the bug.

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