Improve output of XHTML comments.

(i)  Validate even for comments when outputting XHTML.
(ii) Output comments as divs hidden by default. Then people
     can display them other ways if they wish.

git-svn-id: svn://svn.lyx.org/lyx/lyx-devel/trunk@40400 a592a061-630c-0410-9148-cb99ea01b6c8

lib/layouts/stdinsets.inc

@@ -87,8 +87,13 @@ InsetLayout Note:Comment
 	EndFont
 	MultiPar              true
 	Display               false
-	HTMLTag               !--
-	HTMLIsBlock           false
+	HTMLTag               div
+	HTMLIsBlock           true
+  HTMLStyle
+    div.note_comment {
+      display: none;
+    }
+  EndHTMLStyle
 End
 
 
@@ -121,6 +126,7 @@ InsetLayout Note:Greyedout
 	EndFont
 	MultiPar              true
 	Display               false
+	HTMLInnerTag div
 	HTMLStyle
 		div.note_greyedout {
 			display: inline;

src/insets/InsetNote.cpp

@@ -310,6 +310,10 @@ void InsetNote::validate(LaTeXFeatures & features) const
 	switch (params_.type) {
 	case InsetNoteParams::Comment:
 		features.require("verbatim");
+		if (features.runparams().flavor == OutputParams::HTML)
+			// we do output this but set display to "none" by default,
+			// but people might want to use it.
+			InsetCollapsable::validate(features);
 		break;
 	case InsetNoteParams::Greyedout:
 		features.require("color");