Miscellaneous Observatory UI improvements

runtime/bin/vmservice/client/lib/src/elements/isolate_profile.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library isolate_profile_element;
 
 import 'dart:html';
 import 'observatory_element.dart';
 import 'package:logging/logging.dart';
 import 'package:observatory/service.dart';
@@ skipping 216 matching lines @@
     return 'padding-left: ${row.depth * 16}px;';
   }
 
   @observable String coloring(TableTreeRow row) {
     const colors = const ['active', 'success', 'warning', 'danger', 'info'];
     var index = row.depth % colors.length;
     return colors[index];
   }
 
   @observable void toggleExpanded(Event e, var detail, Element target) {
+    // We only want to expand a tree row if the target of the click is
+    // the table cell (passed in as target) or the span containing the
+    // expander symbol (#expand).
+    if ((e.target.id != 'expand') && (e.target != target)) {
+      // Target of click was not the expander span or the table cell.
+      return;
+    }
     var row = target.parent;
     if (row is TableRowElement) {
       // Subtract 1 to get 0 based indexing.
       tree.toggle(row.rowIndex - 1);
     }
   }
-
 }