[css-ui-4] Record issue about the computed value of user-select

Author: frivoal

css-ui-4/Overview.bs

@@ -436,6 +436,12 @@ Omitted values are set to their initial values.
 	or a <a href="http://www.w3.org/TR/html/forms.html#mutability">mutable</a> form control with textual content,
 	such as <{textarea}>.
 
+	Issue: Should there be constraints
+	on what happens to the computed value
+	on elements that are editable descendants of editing hosts?
+	The semantics are not obvious.
+	Maybe ''user-select/none'' should compute to ''text'',
+	or maybe all values should compute to ''text''.
 
 	<dl dfn-type=value dfn-for=user-select>
 		<dt><dfn>auto</dfn>