Deprecate/Remove merror

[fred-wang]

Opening this to discuss whether we should deprecate/remove merror from MathML core/full.

It seems to me generally people won't publish content with errors, unless they were generated from e.g. LaTeX or Computer Algebra system.

[fred-wang]

My understanding of the status is that

• We would keep it in MathML Core defined as an mrow algo with additional style
• Is the suggested merror { outline: solid thin red; background-color: lightYellow; } what we want?
• Borders will require CSS margin/border/padding compatibility #14

[davidcarlisle]

That looks good to me.

[fred-wang]

Resolved on 2019/06//03 as in #70 (comment)
Core spec has been updated: https://mathml-refresh.github.io/mathml-core/#merror

[NSoiffer]

Only remaining thing is to write a test to make sure style sheet (color, etc) is being implemented.

[fred-wang]

cc @rwlbuis

Adding back mathml core label since we still need to write tests. I think we have tests but they follow chromium's style which I'm not sure is aligned on the spec.

Also reputting need resolution and spec update in case people want to bikeshed on the "Is the suggested merror { outline: solid thin red; background-color: lightYellow; } what we want?"

[bkardell]

This doesn't seem worth bikeshedding as it is at best a suggestion. I'm not sure how there could be something nomative in that? Could there?

[fred-wang]

well, we just need to decide something to put in the UA stylesheet. If everybody is ok with "merror { outline: solid thin red; background-color: lightYellow; } " then we can choose that.

[fred-wang]

This doesn't seem worth bikeshedding as it is at best a suggestion. I'm not sure how there could be something nomative in that? Could there?

Also, merror affects some tests so we need to decide a default value. Authors/Users can always change it if they don't like, so I don't think the exact values matters.

Chromium has the following rules:
merror {
color: red;
background-color: lightYellow;
}

Gecko has the following rule:
merror {
display: block;
font-family: sans-serif;
font-weight: bold;
white-space: pre;
margin: 1em;
padding: 1em;
border-width: thin;
border-style: inset;
border-color: red;
font-size: 14pt;
background-color: lightyellow;
}

WebKit has this:
merror {
outline: solid thin red;
font-weight: bold;
font-family: sans-serif;
background-color: lightYellow;
}

It's better not to modify the text style and we don't really explain how to handle outline in the core spec, so a yellow background and border (with optionally padding/margin) seems best.

[fred-wang]

test added