Add thread dots to note header icon, disable comments on closed nodes

modules/ui/note_editor.js

@@ -176,7 +176,7 @@ export function uiNoteEditor(context) {
 
         buttonSection.select('.comment-button')   // select and propagate data
             .attr('disabled', function(d) {
-                return d.newComment ? null : true;
+                return (d.status === 'open' && d.newComment) ? null : true;
             })
             .on('click.save', function(d) {
                 this.blur();    // avoid keeping focus on the button - #4641

modules/ui/note_header.js

@@ -8,7 +8,10 @@ export function uiNoteHeader() {
 
     function noteHeader(selection) {
         var header = selection.selectAll('.note-header')
-            .data([_note], function(d) { return d.status + d.id; });
+            .data(
+                (_note ? [_note] : []),
+                function(d) { return d.status + d.id; }
+            );
 
         header.exit()
             .remove();
@@ -26,6 +29,15 @@ export function uiNoteHeader() {
             .attr('class', 'preset-icon-28')
             .call(svgIcon('#iD-icon-note', 'note-fill'));
 
+        iconEnter.each(function(d) {
+            if (d.comments.length > 1) {
+                iconEnter
+                    .append('div')
+                    .attr('class', 'note-icon-annotation')
+                    .call(svgIcon('#iD-icon-more', 'note-annotation'));
+            }
+        });
+
         headerEnter
             .append('div')
             .attr('class', 'note-header-label')