Fix bar graph Y-axis scale with stacking bar graphs.

lib/timeline/component/LineGraph.js

@@ -1014,6 +1014,7 @@ LineGraph.prototype._convertXcoordinates = function (datapoints) {
   var toScreen = this.body.util.toScreen;
   for (var i = 0; i < datapoints.length; i++) {
     datapoints[i].screen_x = toScreen(datapoints[i].x) + this.props.width;
+    datapoints[i].screen_y = datapoints[i].y; //starting point for range calculations
   }
 };
 

lib/timeline/component/graph2d_types/bar.js

@@ -73,7 +73,7 @@ Bargraph.draw = function (groupIds, processedGroupData, framework) {
       intersections[key].resolved += 1;
 
       if (group.options.stack === true) {
-        if (combinedData[i].y < group.zeroPosition) {
+        if (combinedData[i].screen_y < group.zeroPosition) {
           heightOffset = intersections[key].accumulatedNegative;
           intersections[key].accumulatedNegative += group.zeroPosition - combinedData[i].screen_y;
         }
@@ -96,7 +96,7 @@ Bargraph.draw = function (groupIds, processedGroupData, framework) {
         screen_x:combinedData[i].screen_x,
         screen_y:combinedData[i].screen_y - heightOffset,
         groupId: combinedData[i].groupId,
-        label: combinedData[i].label,
+        label: combinedData[i].label
       };
       Points.draw([pointData], group, framework, drawData.offset);
       //DOMutil.drawPoint(combinedData[i].x + drawData.offset, combinedData[i].y, group, framework.svgElements, framework.svg);