Implement dynamic window title management based on active dock tabs

app/display/representation-javafx/src/main/java/org/csstudio/display/builder/representation/javafx/JFXStageRepresentation.java

@@ -49,7 +49,6 @@ public JFXStageRepresentation(final Stage stage)
     public Parent configureStage(final DisplayModel model, final Consumer<DisplayModel> close_request_handler)
     {
         final String name = model.getDisplayName();
-        stage.setTitle(name);
 
         //  The following trick is necessary because keys cannot be longer than 80 characters.
         final String hexName = Integer.toHexString(name.hashCode()).toLowerCase();

core/ui/src/main/java/org/phoebus/ui/application/Messages.java

@@ -184,6 +184,7 @@ public class Messages
     public static String WebBrowser;
     public static String Welcome;
     public static String Window;
+    public static String WindowTitleFormat;
 
     static
     {

core/ui/src/main/java/org/phoebus/ui/application/PhoebusApplication.java

@@ -80,11 +80,7 @@
 import org.phoebus.ui.dialog.DialogHelper;
 import org.phoebus.ui.dialog.ListPickerDialog;
 import org.phoebus.ui.dialog.OpenFileDialog;
-import org.phoebus.ui.docking.DockItem;
-import org.phoebus.ui.docking.DockItemWithInput;
-import org.phoebus.ui.docking.DockPane;
-import org.phoebus.ui.docking.DockPaneListener;
-import org.phoebus.ui.docking.DockStage;
+import org.phoebus.ui.docking.*;
 import org.phoebus.ui.help.OpenAbout;
 import org.phoebus.ui.help.OpenHelp;
 import org.phoebus.ui.internal.MementoHelper;
@@ -547,6 +543,8 @@ private void startUI(final MementoTree memento, final JobMonitor monitor) throws
             closeMainStage();
         });
 
+        StageTitleManager.bindStageTitlesToActiveTabs(main_stage);
+
         DockPane.addListener(dock_pane_listener);
         DockPane.setActiveDockPane(DockStage.getDockPanes(main_stage).get(0));
         monitor.done();

core/ui/src/main/java/org/phoebus/ui/docking/DockPane.java

@@ -520,11 +520,6 @@ private void doAutoHideTabs(final Scene scene)
                 throw new IllegalStateException("Expected DockItem, got " + tab);
             stage.titleProperty().bind(((DockItem)tab).labelTextProperty());
         }
-        else
-        {   // Fixed title
-            stage.titleProperty().unbind();
-            stage.setTitle(Messages.FixedTitle);
-        }
     }
 
     /** @param tabs One or more tabs to add */
@@ -533,6 +528,8 @@ public void addTab(final DockItem... tabs)
         getTabs().addAll(tabs);
         // Select the newly added tab
         getSelectionModel().select(getTabs().size()-1);
+        // Set this as the active dock pane
+        setActiveDockPane(this);
     }
 
     /** @return All {@link DockItem}s in this pane (safe copy) */

core/ui/src/main/java/org/phoebus/ui/docking/DockStage.java

@@ -164,7 +164,6 @@ else if(layout.getChildren().get(0) instanceof SplitPane){
 
         final Scene scene = new Scene(layout, geometry.width, geometry.height);
         stage.setScene(scene);
-        stage.setTitle(Messages.FixedTitle);
         // Set position
         stage.setX(geometry.x);
         stage.setY(geometry.y);

core/ui/src/main/java/org/phoebus/ui/docking/SplitDock.java

@@ -184,6 +184,16 @@ else if (dock_parent instanceof SplitPane) { // "dock_parent instanceof SplitPan
             return;
         }
 
+        // If the dock pane that has just been merged is active,
+        // switch the active dock pane to the first pane found in the other child
+        if (empty_dock == DockPane.getActiveDockPane()) {
+            if (child instanceof DockPane dockPane) {
+                DockPane.setActiveDockPane(dockPane);
+            } else if (child instanceof SplitDock splitDock) {
+                splitDock.findAndActivateDockPane();
+            }
+        }
+
         // Tell child about its new dock_parent
         if (child instanceof DockPane)
             ((DockPane)child).setDockParent(dock_parent);
@@ -261,6 +271,18 @@ private boolean isEmptyDock(final Node item)
         return false;
     }
 
+    private void findAndActivateDockPane() {
+        // switch the active dock pane to the first pane found in this split or in any nested split
+        for (Node child : getItems()) {
+            if (child instanceof DockPane dockPane) {
+                DockPane.setActiveDockPane(dockPane);
+                return;
+            } else if (child instanceof SplitDock splitDock) {
+                splitDock.findAndActivateDockPane();
+            }
+        }
+    }
+
     @Override
     public String toString()
     {

core/ui/src/main/java/org/phoebus/ui/docking/StageTitleManager.java

@@ -0,0 +1,68 @@
+package org.phoebus.ui.docking;
+
+import javafx.beans.binding.Bindings;
+import javafx.beans.binding.StringExpression;
+import javafx.stage.Stage;
+import org.phoebus.ui.application.Messages;
+
+import java.util.List;
+import java.util.logging.Logger;
+
+/**
+ * Helper class to manage the window title.
+ */
+public class StageTitleManager {
+
+    private static final DockPaneListener listener = StageTitleManager::setStageTitleToTabTitle;
+
+    // This class is only a static utility, so it should not be instantiated.
+    private StageTitleManager() {}
+
+    public static void bindStageTitlesToActiveTabs(Stage mainStage) {
+        // this will listen to all tab focus events and set the stage title
+        // of the stage in which the tab is located to the formatted title.
+        DockPane.addListener(listener);
+
+        // This listener is passed down to all child panes when a split occurs,
+        // so it fires when any pane in the main stage becomes empty.
+        // Therefore, we have to check if all panes are empty.
+        DockStage.getDockPanes(mainStage).get(0).addDockPaneEmptyListener(() -> {
+            List<DockPane> panes = DockStage.getDockPanes(mainStage);
+            for (DockPane pane : panes) {
+                if (!pane.getDockItems().isEmpty()) {
+                    // If any pane has items, we don't need to set the title to default
+                    return;
+                }
+            }
+            // If all panes are empty, set the stage title to the default
+            mainStage.titleProperty().unbind();
+            setStageTitleToDefault(mainStage);
+        });
+    }
+
+    private static void setStageTitleToTabTitle(DockItem dockItem) {
+        if (dockItem == null) {
+            return;
+        }
+        DockPane pane = dockItem.getDockPane();
+        // I don't think this is ever true,
+        // but better to have it and not need it than the other way around
+        if (pane == null) {
+            return;
+        }
+        pane.deferUntilInScene(scene -> {
+            if (scene.getWindow() instanceof Stage stage) {
+                if (DockPane.getActiveDockPane() != pane) {
+                    // If the dock pane is not active, don't do anything
+                    return;
+                }
+                StringExpression exp = Bindings.format(Messages.WindowTitleFormat, dockItem.labelTextProperty());
+                stage.titleProperty().bind(exp);
+            }
+        });
+    }
+
+    private static void setStageTitleToDefault(Stage stage) {
+        stage.setTitle(Messages.FixedTitle);
+    }
+}

core/ui/src/main/resources/org/phoebus/ui/application/messages.properties

@@ -170,3 +170,4 @@ UnsavedChanges_wouldYouLikeToSaveAnyChangesBeforeReplacingTheLayout=Would you li
 WebBrowser=Web Browser
 Welcome=Welcome
 Window=Window
+WindowTitleFormat=CS-Studio: %s

core/ui/src/main/resources/org/phoebus/ui/application/messages_fr.properties

@@ -168,3 +168,4 @@ UnsavedChanges_wouldYouLikeToSaveAnyChangesBeforeReplacingTheLayout=Voulez-vous
 WebBrowser=Navigateur Web
 Welcome=Bienvenue
 Window=Fen\u00EAtre
+WindowTitleFormat=CS-Studio: %s