[css-ui-4] Close issue about possible need for appearance:button

Closes issue #802

css-ui-4/Overview.bs

@@ -827,6 +827,7 @@ every time we introduced a new value,
 we would change what ''appearance/auto'' computes to on some elements,
 which doesn't sounds desirable.
 
+<div class="note">
 Note: This specification intentionally refrains from making the appearance
 of all possible form controls and sub-controls available as values,
 as had previously been attempted by earlier proposals for this property
@@ -842,11 +843,23 @@ Instead, this specification only provides
 ''appearance/auto'', ''appearance/none''.
 UAs cannot therefore use the 'appearance' property
 in the UA stylesheet to give each control its native look and feel,
-and must use ''appearance:auto'' instead.
+and must use ''appearance: auto'' instead.
+
+<div class="advisement">
+Authors desiring to make certain elements in their document
+look and behave like native form controls
+should use the correct element in the markup language of the document
+rather than attempt to use this property or its experimental variants.
+</div>
+
+Future version of this specification may add a few more values
+for commonly desired appearances
+if compability with content written for experimental implementations proves problematic.
+So far, experience indicates that this is not the case.
+Even if this were to happen,
+it is not anticipated that the property would grow to cover all possible controls and sub-controls.
+</div>
 
-Issue: IE supports -webkit-appearance, and also includes the textfield and button values.
-Presumably this was done due to compatibility problems,
-so we may need to include it as well.
 
 <dl dfn-type=value dfn-for=appearance>
 	<dt><dfn>auto</dfn>