spec selectors

Issues for Level 4

• Lift restriction preventing combinators in :any/:not in the fast profile?
• Anything else that should be moved from complete to fast profile?
• Syntax of subject indicator
• Comma-separated [attr] values, for easy OR matching?
• Numeric [attr] comparators?
• Name of :any-link - maybe put "link" first in the name, like :link-any?
• Does :local-link(n) force N path segments to match, or can a document with a shorter url still create a match? (Example: in https://github.com/tabatkins/css-preprocessor, does :local-link(2) mean "same user and repository only", or does it allow "https://github.com/tabatkins", thus implicitly allowing "same user, but no specified repo"?)
• Naming the drag-and-drop pseudoclasses
• Just point the An+B grammar section to Syntax, now that it's accepted?
• dbaron is uncertain about the reference and column combinators, the :matches() syntax (naming? something else?) and the subject indicator.

Brainstorming for Selectors Level 5

• Selectors 3 PR
• Selectors 4 ED

Ideas to consider

• numeric attribute selectors, e.g. [height>2], [count<=5], [balance<0], [#row>1]
• ::quote-start and ::quote-end, to match characters with the Quotation_Mark property that are direct children of the element and that are immediately inside the start and end (respectively) of the element, ignoring White_Space characters. (This would help a lot with <q> in HTML5.)
• [:placeholder](https://developer.mozilla.org/en/CSS/%3a-moz-placeholder) - matches form elements displaying placeholder text. This allows web developers and theme designers to customize the appearance of placeholder text, which is a light grey color by default. This may not work well if you've changed the background color of your form fields to be a similar color, for example, so you can use this pseudo-class to change the placeholder text color.
• [::window](http://lists.w3.org/Archives/Public/www-style/2008Nov/0466.html) pseudo-element
• limited descendant combinator (more info) – foo>bar, foo>:not(bar)>bar, … comes hardly close
• Better definition of ::first-letter, see also note in Selectors L3
• ::first-words(n), ::first-lines(n), ::nth-line(an+b), ::last-line etc.
• semantic pseudo-class selectors e.g. for headings or "visible" elements (i.e. not <script> or <style>) akin to :link etc.
• Clarify that first formatted line is not triggered when preceded by a block http://wiki.csswg.org/spec/css2.1#issue-268
• UA hint pseudo-element selectors ::typo, ::match etc.
• empty input selector
• more of the user action pseudo-classes
• More time pseudo-classes: :time([ before <time> | after <time> | <time> to <time> ])
• :only-whitespace: :empty is kinda useless, since it requires you to have nothing between the start and end tag. This is hostile to common markup patterns which might put the end tag on a separate line.

Ideas superseded by other features

• relationship selectors, e.g.:
  • to select cells in a column: col.foo // td
  • to select labels applying to an input control: !label /for/ input
  • to select map elements associated with an image: img /usemap/ map
  • to select arbitrary associated elements: x /href/ y
• only-child-parent Most use cases for the parent selector care only about the only child. This doesn't have the same perf implications as a general parent selector. – solved with :matches() and $
• dynamic values selector - already handled by ::value pseudo-element in CSS3-UI.