[css-highlight-api] negative priorities

[frivoal]

Assuming we continue having numerical priorities (see #4591):

• If priorities are stored as integers (see [css-highlight-api] should priority be a floating point number or an integer? #4592), should we allow negative ones?

• If negative integers or doubles are used, does a negative priority mean placement below the built-in highlights in the stacking order, and a positive number above them?

[hober]

If we go with numbers at all for this, I think we should allow negative numbers. A library author may want to say "my feature is cool, but if anything else is using the highlight api on this page, they should win over me."

[sanketj]

@frivoal @hober @fantasai I don't see any additional problems with negative numbers, my thought is that we should allow them. That would be consistent with z-index. Are you all okay with that?

[frivoal]

yes, let's allow them.

[sanketj]

Left the priority attribute as (implicitly) 'signed'. Closing this issue.