Added JSNI method to show reset zoom button after zooming via API

java/com.sap.sailing.gwt.ui/src/main/java/com/sap/sailing/gwt/ui/client/shared/charts/AbstractRaceChart.java

@@ -226,8 +226,15 @@ public abstract class AbstractRaceChart<SettingsType extends Settings> extends A
     public void onTimeZoomChanged(Date zoomStartTimepoint, Date zoomEndTimepoint) {
         changeMinMaxAndExtremesInterval(zoomStartTimepoint, zoomEndTimepoint, true);
         // Probably there is a function for this in a newer version of highcharts: http://jsfiddle.net/mqz3N/1071/ 
-        // chart.showResetZoom();
+        this.showResetZoom();
     }
+    
+    // Because there is no method within highcharts Java API, the respective JS method is called via JSNI. 
+    private native void showResetZoom() /*-{
+        var chartObject = this.@com.sap.sailing.gwt.ui.client.shared.charts.AbstractRaceChart::chart;
+        var chart = chartObject.@org.moxieapps.gwt.highcharts.client.Chart::getNativeChart()();
+        if (chart) chart.showResetZoom();
+    }-*/;
 
     @Override
     public void onTimeRangeChanged(Date fromTime, Date toTime) {