[css-multicol-1] Clarify when column-span:all creates a formatting context

frivoal · frivoal · commit a8634b969002 · 2017-04-06T02:14:01.000+09:00
Closes #1074
diff --git a/css-multicol/Overview.bs b/css-multicol/Overview.bs
@@ -15,6 +15,7 @@ Previous Version: https://www.w3.org/TR/2005/WD-css3-multicol-20051215/
 Previous Version: https://www.w3.org/TR/2001/WD-css3-multicol-20010118/
 Previous Version: http://www.w3.org/1999/06/WD-css3-multicol-19990623
 Editor: Håkon Wium Lie, Opera Software, howcome@opera.com
+Editor: Florian Rivoal, On behalf of Bloomberg, https://florian.rivoal.net
 Abstract: This specification describes multi-column layouts in CSS, a style sheet language for the web. Using functionality described in the specification, content can be flowed into multiple columns with a gap and a rule between them.
 Link Defaults: css-color (property) color, css21 (property) max-height, css-backgrounds-3 (value) hidden
 </pre>
@@ -945,17 +946,18 @@ Spanning columns</h2>
 			element is automatically balanced across all columns before the
 			element appears. The element establishes a new block formatting
 			context.
+
+			Note: The element establishing a formatting content does not
+			depend of whether the element is a descendent of a multicol or not.
+			When 'column-span' is ''column-span/all'', it always does.
+			This helps with robustness of designs to later revisions
+			that remove the multicol,
+			or when media queries turn the multicol off in some situations.
 	</dl>
 
 	An element that spans more than one column is called a
 	<dfn export>spanning element</dfn> and the box it creates is called a <dfn export>spanner</dfn>.
 
-	<!--
-	This property has no effect on elements that do not fit entirely
-	within the multicol element. Also, if a setting on this property pushes the
-	element outside a multicol element, this property will have no effect.
-	-->
-
 	<div class="example">
 		In this example, an <code>h2</code> element has been added to the
 		sample document after the sixth sentence (i.e., after the word "jkl."). This styling applies:
