Implemented a stable TabResultsPresenter

java/com.sap.sailing.gwt.ui/src/main/java/com/sap/sailing/gwt/ui/client/StringMessages.java

@@ -1353,4 +1353,6 @@ public interface StringMessages extends com.sap.sse.gwt.client.StringMessages, c
     String currentOfTotal(int current, int total);
     String noFinishedRaces();
     String racesOverview();
+    String empty();
+    String runAQuery();
 }

java/com.sap.sailing.gwt.ui/src/main/java/com/sap/sailing/gwt/ui/client/StringMessages.properties

@@ -1322,3 +1322,5 @@ miniLeeaderboardLegendText=Shows the points along with the number of races per c
 currentOfTotal={0,number}/{1,number}
 noFinishedRaces=There are no finished races yet
 racesOverview=Races overview
+empty=Empty
+runAQuery=Run a Query

java/com.sap.sailing.gwt.ui/src/main/java/com/sap/sailing/gwt/ui/client/StringMessages_de.properties

@@ -1312,3 +1312,5 @@ miniLeeaderboardLegendText=Es werden die Punkte und die Anzahl Rennen je Team an
 currentOfTotal={0,number}/{1,number}
 noFinishedRaces=Es wurden noch keine Wettfahrten beendet.
 racesOverview=Wettfahrtübersicht
+empty=Leer
+runAQuery=Führe eine Anfrage aus

java/com.sap.sailing.gwt.ui/src/main/java/com/sap/sailing/gwt/ui/client/StringMessages_ru.properties

@@ -1259,3 +1259,5 @@ miniLeeaderboardLegendText=Shows points along with the number of races per compe
 currentOfTotal={0,number}/{1,number}
 noFinishedRaces=There are no finished races yet
 racesOverview=Races overview
+empty=Empty
+runAQuery=Run a Query

java/com.sap.sailing.gwt.ui/src/main/java/com/sap/sailing/gwt/ui/client/shared/controls/ScrolledTabLayoutPanel.java

@@ -171,7 +171,7 @@ public class ScrolledTabLayoutPanel extends TabLayoutPanel {
         return vPanel;
     }
 
-    private void checkIfScrollButtonsNecessary() {
+    public void checkIfScrollButtonsNecessary() {
         // Defer size calculations until sizes are available, when calculating immediately after
         // add(), all size methods return zero
         Scheduler.get().scheduleDeferred(new Scheduler.ScheduledCommand() {
@@ -195,7 +195,7 @@ public class ScrolledTabLayoutPanel extends TabLayoutPanel {
     
     public void scrollToTab(int tabNumber) {
         Widget tab = getTab(tabNumber);
-        if (tab == null)
+        if (tab == null || !isScrollingNecessary())
             return;
         
         int oldLeft = parsePosition(tabBar.getElement().getStyle().getLeft());
@@ -232,6 +232,10 @@ public class ScrolledTabLayoutPanel extends TabLayoutPanel {
             }
         }.run(SCROLL_ANIMATION_SPEED);
     }
+    
+    private boolean isScrollingNecessary() {
+        return isScrollingToLeftNecessary() || isScrollingToRightNecessary();
+    }
 
     private boolean isScrollingToRightNecessary() {
         Widget lastTab = getLastTab();

java/com.sap.sailing.gwt.ui/src/main/java/com/sap/sailing/gwt/ui/datamining/DataMiningResources.java

@@ -14,4 +14,7 @@ public interface DataMiningResources extends ClientBundle {
     @Source("com/sap/sailing/gwt/ui/client/images/arrow_right.png")
     ImageResource arrowRightIcon();
 
+    @Source("com/sap/sailing/gwt/ui/client/images/plusicon_small.png")
+    ImageResource plusIcon();
+
 }

java/com.sap.sailing.gwt.ui/src/main/java/com/sap/sailing/gwt/ui/datamining/presentation/TabResultsPresenter.java

@@ -1,12 +1,18 @@
 package com.sap.sailing.gwt.ui.datamining.presentation;
 
+import java.util.HashMap;
+import java.util.Map;
+
 import com.google.gwt.core.shared.GWT;
 import com.google.gwt.dom.client.Style.Unit;
 import com.google.gwt.event.dom.client.ClickEvent;
 import com.google.gwt.event.dom.client.ClickHandler;
+import com.google.gwt.event.logical.shared.BeforeSelectionEvent;
+import com.google.gwt.event.logical.shared.BeforeSelectionHandler;
 import com.google.gwt.user.client.ui.HTML;
 import com.google.gwt.user.client.ui.HorizontalPanel;
 import com.google.gwt.user.client.ui.Image;
+import com.google.gwt.user.client.ui.Label;
 import com.google.gwt.user.client.ui.Widget;
 import com.sap.sailing.gwt.ui.client.StringMessages;
 import com.sap.sailing.gwt.ui.client.shared.controls.ScrolledTabLayoutPanel;
@@ -21,6 +27,7 @@ public class TabResultsPresenter implements ResultsPresenter<Number> {
     private final StringMessages stringMessages;
     
     private final ScrolledTabLayoutPanel tabPanel;
+    private final Map<Widget, ResultsPresenter<Number>> presentersMappedByHeader;
     
     public TabResultsPresenter(StringMessages stringMessages) {
         this.stringMessages = stringMessages;
@@ -28,6 +35,26 @@ public class TabResultsPresenter implements ResultsPresenter<Number> {
         tabPanel = new ScrolledTabLayoutPanel(30, Unit.PX, resources.arrowLeftIcon(), resources.arrowRightIcon());
         tabPanel.setAnimationDuration(0);
         tabPanel.getElement().getStyle().setMarginTop(10, Unit.PX);
+        presentersMappedByHeader = new HashMap<>();
+        
+        addNewTabTab();
+        addTabAndFocus();
+    }
+
+    private void addNewTabTab() {
+        Label widget = new Label("This should never be shown");
+        Image header = new Image(resources.plusIcon());
+        tabPanel.add(widget, header);
+        // This is necessary to stop the selection of this pseudo tab
+        tabPanel.addBeforeSelectionHandler(new BeforeSelectionHandler<Integer>() {
+            @Override
+            public void onBeforeSelection(BeforeSelectionEvent<Integer> event) {
+                if (event.getItem() == tabPanel.getWidgetCount() - 1) {
+                    event.cancel();
+                    addTabAndFocus();
+                }
+            }
+        });
     }
 
     @Override
@@ -37,59 +64,76 @@ public class TabResultsPresenter implements ResultsPresenter<Number> {
 
     @Override
     public void showResult(QueryResult<Number> result) {
-        ResultsPresenter<Number> tabPresenter = addTabAndFocus(result.getResultSignifier());
-        tabPresenter.showResult(result);
+        getSelectedHeader().setText(result.getResultSignifier());
+        getSelectedPresenter().showResult(result);
     }
 
     @Override
     public void showError(String error) {
-        ResultsPresenter<Number> tabPresenter = addTabAndFocus(stringMessages.error());
-        tabPresenter.showError(error);
+        getSelectedHeader().setText(stringMessages.error());
+        getSelectedPresenter().showError(error);
     }
 
     @Override
     public void showError(String mainError, Iterable<String> detailedErrors) {
-        ResultsPresenter<Number> tabPresenter = addTabAndFocus(stringMessages.error());
-        tabPresenter.showError(mainError, detailedErrors);
+        getSelectedHeader().setText(stringMessages.error());
+        getSelectedPresenter().showError(mainError, detailedErrors);
     }
 
     @Override
     public void showBusyIndicator() {
-        // Do nothing here. A management of the different tabs is necessary to handle this.
-    }
-
-    private ResultsPresenter<Number> addTabAndFocus(String headerText) {
-        CloseableTabHeader tabHeader = new CloseableTabHeader(headerText);
-        ResultsChart tabPresenter = new ResultsChart(stringMessages);
-        tabPanel.add(tabPresenter.getWidget(), tabHeader.getWidget());
-        tabPanel.selectTab(tabPanel.getWidgetCount() - 1);
-        tabPanel.scrollToTab(tabPanel.getWidgetCount() - 1);
-        return tabPresenter;
+        getSelectedHeader().setText(stringMessages.runningQuery());
+        getSelectedPresenter().showBusyIndicator();
     }
     
-    private class CloseableTabHeader {
+    private CloseableTabHeader getSelectedHeader() {
+        return (CloseableTabHeader) tabPanel.getTabWidget(tabPanel.getSelectedIndex());
+    }
+
+    private ResultsPresenter<Number> getSelectedPresenter() {
+        return presentersMappedByHeader.get(getSelectedHeader());
+    }
+
+    private void addTabAndFocus() {
+        CloseableTabHeader tabHeader = new CloseableTabHeader();
+        ResultsChart tabPresenter = new ResultsChart(stringMessages);
+        tabPresenter.showError(stringMessages.runAQuery());
+        presentersMappedByHeader.put(tabHeader, tabPresenter);
         
-        private final HorizontalPanel widget;
+        tabPanel.insert(tabPresenter.getWidget(), tabHeader, tabPanel.getWidgetCount() - 1);
+        int presenterIndex = tabPanel.getWidgetIndex(tabPresenter.getWidget());
+        tabPanel.selectTab(presenterIndex);
+        tabPanel.scrollToTab(presenterIndex);
+    }
+    
+    private void removeTab(CloseableTabHeader header) {
+        header.removeFromParent();
+        presentersMappedByHeader.remove(header);
+    }
+    
+    private class CloseableTabHeader extends HorizontalPanel {
         
-        public CloseableTabHeader(String text) {
-            widget = new HorizontalPanel();
-            HTML label = new HTML(text);
+        private final HTML label;
+        
+        public CloseableTabHeader() {
+            label = new HTML(stringMessages.empty());
             label.getElement().getStyle().setMarginRight(5, Unit.PX);
-            widget.add(label);
+            this.add(label);
             Image closeImage = new Image(resources.closeIcon());
             closeImage.addClickHandler(new ClickHandler() {
                 @Override
                 public void onClick(ClickEvent event) {
-                    if (tabPanel.getWidgetCount() > 1) {
-                        widget.removeFromParent();
+                    if (tabPanel.getWidgetCount() > 2) {
+                        removeTab(CloseableTabHeader.this);
                     }
                 }
             });
-            widget.add(closeImage);
+            this.add(closeImage);
         }
         
-        public HorizontalPanel getWidget() {
-            return widget;
+        public void setText(String text) {
+            label.setText(text);
+            tabPanel.checkIfScrollButtonsNecessary();
         }
         
     }