Forum thread in http://moodle.org/mod/forum/discuss.php?d=77723

• Is this a problem in JAWS 7 (as implied by "Environment" section above)? I've tried skipping the Course News block (that is, an anchor within the same page) without problems on JAWS 7 on Internet Explorer 6/ XP Professional.
• When JAWS "hangs and becomes unresponsive" what is your browser doing? (I accept it may be hard to tell what your browser is doing, if you're relying on JAWS!) Are you using Internet Explorer 6?
• As you say the stylesheets are large - BUT they should be cached for 10 minutes in IE6 and other browsers, see this old bug MDL-5099 (We may need to look at this again). How do you know that stylesheets are the problem?

A slight modification for weblib.php, theme_setup function:
if (empty($USER->screenreader))
TO
if (empty($USER->screenreader) || $USER->screenreader==0)

Your patch basically works in terms of mechanics (though we'd want to look at the many 'display:none' again!)
but a) the 'screenreader' setting on the user profile is undocumented, and I'm wary of using it, and b) I think that some screenreader users do care about visual styles - if you have low vision instead of complete blindness, or if you're a non-native speaker using a screenreader to help with pronunciation, etc.

Thanks, Nick

It is a problem in 7.0 but it is fixed in 7.10 (and 8.0 for that matter).

> - When JAWS "hangs and becomes unresponsive" what is your browser
> doing? (I accept it may be hard to tell what your browser is
> doing, if you're relying on JAWS!) Are you using Internet Explorer
> 6?

As far as i can tell, nothing.

The page is already rendered correctly before the delays. Neither JAWS nor IE consumes any significant amount of CPU-time when this happens.

> - As you say the stylesheets are large - BUT they should be cached
> for 10 minutes in IE6 and other browsers, see this old bug
> MDL-5099 (We may need to look at this again). How do you know that
> stylesheets are the problem?

The stylesheets are not downloaded any more often than usual, the delays are not caused by waiting for network traffic.

By removing the links to the stylesheets completely from moodle pages, the problem also disappears. Also you can cause the same problem on any webpage by linking in a stylesheet filled with 7000 css rulesets.

Therefore a large stylesheet is a necessary and sufficient condition for causing this problem.

A large stylesheet in this case is one with many css rulesets. The css-rulesets may be empty and they don't have to apply to any elements in the webpage. But a troublesome stylesheet with all code commented
out do not cause these problems.

> A slight modification for weblib.php, theme_setup function:
> if (empty($USER->screenreader))
> TO
> if (empty($USER->screenreader) || $USER->screenreader==0)

Thanks! I updated the patch.

> but a) the 'screenreader' setting on the user profile is
> undocumented, and I'm wary of using it, and

Another solution is to implement it as a theme. We have done both.

> b) I think that some screenreader users do care about visual styles
> - if you have low vision instead of complete blindness, or if you're
> a non-native speaker using a screenreader to help with
> pronunciation, etc.

That concerns me too. I have no exhaustive knowledge of how screenreaders are used.

Ideally the setting should have a better name, and should probably be connected to other profile settings that are appropriate to make when using this, such as making sure the HTML-editor is turned off.

Also, it might be appropriate to ask the users about these settings as part of the signup process.

There are other settings you also might consider in addition to this, such as picking a theme with high contrast and large fonts.