[css-ui-4] Change value mapping logic of user-select to used-value time

Closes w3c#3344

Author: frivoal

css-ui-4/Overview.bs

@@ -1506,15 +1506,15 @@ avoiding accidental selections of neighbouring content.
 	Initial: auto
 	Inherited: no
 	Applies to: all elements, and optionally to the ''::before'' and ''::after'' pseudo elements
-	Computed value: See below
+	Computed value: specified keyword
 	Animation type: not animatable
 </pre>
 
 User Agents must not apply the 'user-select' property to
 the ''::first-line'' and ''::first-letter'' pseudo elements.
 
 Note: The UA may apply this property to the ''::before'' and ''::after'' pseudo elements.
-If it does, ''user-select/auto'' value computes to ''user-select/none'' on these pseudos,
+If it does, ''user-select/auto'' value maps to a [=used value=] of ''user-select/none'' on these pseudos,
 but other values can be specified.
 This preserves the legacy behavior of generated content not being selectable or copyable,
 which is appropriate when these pseudos are used for decorative purposes.
@@ -1535,21 +1535,21 @@ through this mechanism,
 UAs should also make this content findable through their search function.
 
 Issue: Should it also apply to ''::marker''? To <a>page-margin boxes</a>?
-Should the computed value of '''user-select/auto'' also be ''user-select/none'',
+Should the [=used value=] of '''user-select/auto'' also be ''user-select/none'',
 or would ''user-select/text'' be more appropriate?
 
-The computed value is the specified value,
+The [=used value=] is the same as the [=computed value=],
 except:
 
 <ol>
 	<li>
 		on <a>editable element</a>s
-		where the computed value is always ''user-select/contain''
-		regardless of the specified value
+		where the [=used value=] is always ''user-select/contain''
+		regardless of the [=computed value=]
 
 	<li>
-		when the specified value is ''user-select/auto'',
-		which computes one of the other values as defined below
+		when the [=computed value=] is ''user-select/auto'',
+		in which case the [=used value=] one of the other values as defined below
 </ol>
 
 For the purpose of this specification,
@@ -1559,41 +1559,41 @@ or a <a spec=html>mutable</a> form control with textual content,
 such as <{textarea}>.
 
 Issue: Should there be constraints
-on what happens to the computed value
+on what happens to the used value
 on elements that are editable descendants of editing hosts?
 The semantics are not obvious.
-Maybe ''user-select/none'' should compute to ''user-select/text'',
-or maybe all values should compute to ''user-select/text''.
+Maybe ''user-select/none'' should map to ''user-select/text'',
+or maybe all values should map to ''user-select/text''.
 
 <dl dfn-type=value dfn-for=user-select>
 	<dt><dfn>auto</dfn>
 	<dd>
-		The computed value of ''user-select/auto'' is determined as follows:
+		The [=used value=] of ''user-select/auto'' is determined as follows:
 
 		<ul>
 			<li>
 				On the ''::before'' and ''::after'' pseudo elements,
-				the computed value is ''user-select/none''
+				the used value is ''user-select/none''
 
 			<li>
 				If the element is an <a>editable element</a>,
-				the computed value is ''user-select/contain''
+				the [=used value=] is ''user-select/contain''
 
 			<li>
 				Otherwise,
-				if the computed value of 'user-select' on the parent of this element is ''all'',
-				the computed value is ''all''
+				if the [=used value=] of 'user-select' on the parent of this element is ''all'',
+				the [=used value=] is ''all''
 
 			<li>
 				Otherwise,
-				if the computed value of 'user-select' on the parent of this element is ''user-select/none'',
-				the computed value is ''user-select/none''
+				if the [=used value=] of 'user-select' on the parent of this element is ''user-select/none'',
+				the [=used value=] is ''user-select/none''
 			<li>
-				Otherwise, the computed value is ''user-select/text''
+				Otherwise, the [=used value=] is ''user-select/text''
 		</ul>
 
 		Note: This unusual combination of a non inherited property with an initial value of ''user-select/auto''
-		whose computed value depends on the parent element
+		whose used value depends on the parent element
 		makes it possible to create what is effectively selective inheritance.
 		This was initially proposed by Microsoft in IE to introduce a behavior similar to inheritance
 		except that the ''user-select/contain'' value does not inherit.
@@ -1627,14 +1627,14 @@ or maybe all values should compute to ''user-select/text''.
 		Firefox and Internet explorer behave as prescribed in this specification
 		and do not create a selection at all.
 
-		However, if this element has descendants on which the computed value of 'user-select' is not ''user-select/none'',
+		However, if this element has descendants on which the [=used value=] of 'user-select' is not ''user-select/none'',
 		selections that start and end within these descendants are allowed.
 
 		The UA must allow selections to extend across this element,
 		and must exclude this element from such a selection.
 		An exception is made for UAs which do not support multiple ranges per selection,
 		and they may include this element.
-		If the element has descendants on which 'user-select' does not compute to ''user-select/none'',
+		If the element has descendants on which the [=used value=] of 'user-select' is not ''user-select/none'',
 		these descendants must be included in a selection extending across the element.
 		<span class=note>This specification makes no normative requirement
 		about the behavior of the clipboard.
@@ -1714,10 +1714,10 @@ or maybe all values should compute to ''user-select/text''.
 		If a selection would contain part of the element,
 		then the selection must contain the entire element including all its descendants.
 		If the element is selected
-		and the computed value of 'user-select' on its parent is ''all'',
+		and the [=used value=] of 'user-select' on its parent is ''all'',
 		then the parent must be included in the selection, recursively.
 
-		If this element has descendants on which the computed value of 'user-select' is not ''all''
+		If this element has descendants on which the [=used value=] of 'user-select' is not ''all''
 		and if a selection is entirely contained in these descendants,
 		then the selection is not extended to include this whole element.
 </dl>
@@ -2146,6 +2146,7 @@ the following normative changes have been made:
 	<li>Moved the 'box-sizing' and 'text-overflow' properties to [[CSS-SIZING-3]] and [[CSS-OVERFLOW-4]] respectively.
 	<li>Changed the requirement that the ''cursor/text'' cursor matches the writing mode from MAY to MUST
 	<li>The definition of the appearance property has been significantly reworked to make the design compatible with existing web content
+	<li>The logic that mapped ''user-select: auto'' to various values at computed value time has been changed to used value time
 </ul>
 
 <h3 id=changes-22-09-2015 class=no-num>Changes from the

css-ui-4/issues-fpwd-2015.html

@@ -162,6 +162,14 @@ <h1>CSS Basic User Interface Module Level 4 Disposition of Comments for 2015-09-
 Response: <a href='https://github.com/w3c/csswg-drafts/issues/3196#issuecomment-427736600'>https://github.com/w3c/csswg-drafts/issues/3196#issuecomment-427736600</a>
 Closed:   Accepted
 Resolved: Editorial</pre>
+<pre class='a' id='issue-17'>
+Issue 17. <a href='#issue-17'>#</a>
+Summary:  The computed value rules of user-select is problematic
+From:     Emilio Cobos Álvarez
+Comment:  <a href='https://github.com/w3c/csswg-drafts/issues/3344'>https://github.com/w3c/csswg-drafts/issues/3344</a>
+Response: <a href='https://github.com/w3c/csswg-drafts/issues/3344#issuecomment-466839533'>https://github.com/w3c/csswg-drafts/issues/3344#issuecomment-466839533</a>
+Closed:   Accepted
+Resolved: <a href='https://github.com/w3c/csswg-drafts/issues/3344#issuecomment-467637093'>https://github.com/w3c/csswg-drafts/issues/3344#issuecomment-467637093</a></pre>
 <script>
 (function () {
     var sheet = document.styleSheets[0];

css-ui-4/issues-fpwd-2015.txt

@@ -138,3 +138,11 @@ Comment:  https://github.com/w3c/csswg-drafts/issues/3219
 Response: https://github.com/w3c/csswg-drafts/issues/3196#issuecomment-427736600
 Closed:   Accepted
 Resolved: Editorial
+----
+Issue 17.
+Summary:  The computed value rules of user-select is problematic
+From:     Emilio Cobos Álvarez
+Comment:  https://github.com/w3c/csswg-drafts/issues/3344
+Response: https://github.com/w3c/csswg-drafts/issues/3344#issuecomment-466839533
+Closed:   Accepted
+Resolved: https://github.com/w3c/csswg-drafts/issues/3344#issuecomment-467637093