[css-text-3] Hanging glyphs are ink overflow, but UA make make them scrollable overflow if that would be useful. w3c#4297

Author: fantasai

css-text-3/Overview.bs

@@ -4835,9 +4835,8 @@ Cursive Scripts</h4>
       (The interaction of this measurement and kerning is currently UA-defined;
       the CSSWG <a href="https://github.com/w3c/csswg-drafts/issues/2397">welcomes advice</a> on this point.)
 
-    <p>A <a lt=hang>hanging</a> glyph
-      is still enclosed inside its parent inline box,
-      is still counted as part of the <a>scrollable overflow region</a> [[!CSS-OVERFLOW-3]],
+    <p>A <dfn><a lt=hang>hanging</a> glyph</dfn>
+      is still enclosed inside its parent inline box
       and still participates in text justification:
       its character advance is just not measured when determining
       how much content fits on the line,
@@ -4847,6 +4846,13 @@ Cursive Scripts</h4>
       is re-interpreted as an additional negative margin
       on the affected edge of its parent <a>inline box</a>;
       the line is otherwise laid out as usual.
+      An overflowing [=hanging glyph=] should typically be considered
+      [=ink overflow=] [[!CSS-OVERFLOW-3]]
+      so as to avoid creating unnecessary scrollbars,
+      but the UA may treat it as [=scrollable overflow=]
+      when the content is editable
+      or in other circumstances where treating it as [=scrollable overflow=]
+      would be useful to the user.
 
       <wpt>
         hanging-punctuation/hanging-scrollable-001.html