Updated charted DEP to 0.4.X

packages/charted/lib/charts/behaviors/chart_tooltip.dart

 //
 // Copyright 2014 Google Inc. All rights reserved.
 //
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file or at
 // https://developers.google.com/open-source/licenses/bsd
 //
 
 part of charted.charts;
 
@@ skipping 73 matching lines @@
       }
       _tooltipRoot.append('div')
         ..classed('tooltip-total')
         ..text((formatter != null) ? formatter(total) : total.toString());
     }
 
     // Find the currently selectedMeasures and hoveredMeasures and show
     // tooltip for them, if none is selected/hovered, show all.
     var activeMeasures = [];
     if (showSelectedMeasure) {
-      activeMeasures.addAll(_state.selection);
-      activeMeasures
-          .add(_state.preview != null ? _state.preview : _state.hovered.first);
+      if(_state != null) {
+        activeMeasures.addAll(_state.selection);
+        activeMeasures
+            .add(_state.preview != null
+                ? _state.preview
+                : _state.hovered.first);
+      } else {
+
+        // If state is null, chart tooltip will not capture selection, but only
+        // display for the currently hovered measure column.
+        activeMeasures.add(e.column);
+      }
       if (activeMeasures.isEmpty) {
         for (var series in _area.config.series) {
           activeMeasures.addAll(series.measures);
         }
       }
       activeMeasures.sort();
     }
 
     var data = (showSelectedMeasure) ? activeMeasures : e.series.measures;
 
@@ skipping 79 matching lines @@
   }
 
   FormatFunction _getFormatterForColumn(int column) =>
       _area.data.columns.elementAt(column).formatter;
 
   hide(ChartEvent e) {
     if (_tooltipRoot == null) return;
     _tooltipRoot.style('opacity', '0');
   }
 }