158068 - Document :hover quirk

Status: RESOLVED FIXED

(Core :: CSS Parsing and Computation, defect)

Description

[leonard]

From Bugzilla Helper:
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.1a+) Gecko/20020715
BuildID:    2002071508

When in Quirks mode, the follow selector:
  *:{pseudo-class} ex *:hover
won't work, while a specific tag selector will:
  tag:{pseudo-class} ex b:hover

This isn't documented in the Quirks List
(http://www.mozilla.org/docs/web-developer/quirks/quirklist.html) and seems like
a bug.  The included URL has links to the same CSS code (one in strict mode, one
in quirks mode)

Reproducible: Always
Steps to Reproduce:
1. Visit Page w/ said combination of selectors and quirks mode
2. View CSS not work

Actual Results:  CSS does not work

Expected Results:  CSS should work

Comment 1

[Bill Mason]

->Style system

Comment 2

[leonard]

Oops, tried it with the :focus pseudo-class and it looks like this problem only
affects :hover.  see: http://randomfoo.net/sandbox/mozilla/selector/quirks.html

Comment 3

[Boris Zbarsky [:bzbarsky]]

This is a purposeful quirk to save pages that do things like ":hover{color:
red}" and expect it to only apply to links.  See
http://lxr.mozilla.org/seamonkey/source/content/html/style/src/nsCSSStyleSheet.cpp#3639

David, we should probably add this to the quirk list....  Mind if I do that?

Comment 4

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

Well, I'd been wondering if we really needed it, but we probably do.

Comment 5

[Boris Zbarsky [:bzbarsky]]

Proposed change to the document:

Add

+                        <li>The <code>:hover</code> pseudoclass will only be
applied to links unless the selector includes
+                            tag names, classes, or attributes.</li

at the end of the "Miscellaneous & Style" section.

David, that seem reasonable?

Comment 6

[Boris Zbarsky [:bzbarsky]]

I've checked in the following change:

-			<li>For <a href="http://bugzilla.mozilla.org/show_bug.cgi?id=18817">bug
18817</a>, quirks mode was intended to accept stylesheets in certain cases when
strict mode did not, but the code has since gotten somewhat mangled and doesn't
seem to have much point anymore.</li>
+			<li>The <code>:hover</code> pseudoclass will only be applied to links,
images, and form controls, unless the selector includes tag names, ids, or
attributes.</li>

with the comment:

  Add :hover quirk to list; remove quirk from bug 18817, since the patch for bug
  155421 removed the quirky code.