CSSTUDIO-1997 Add option to open most recently focused tab when closing a tab

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

@@ -176,6 +176,17 @@ public DockItem(final String label)
         createContextMenu();
 
         setOnClosed(event -> handleClosed());
+        setOnCloseRequest(event -> {
+            // Select the previously selected tab:
+            var dockPane = getDockPane();
+            dockPane.tabsInOrderOfFocus.remove(this);
+
+            if (dockPane.tabsInOrderOfFocus.size() > 0) {
+                var tabToSelect = dockPane.tabsInOrderOfFocus.getFirst();
+                var selectionModel = dockPane.getSelectionModel();
+                selectionModel.select(tabToSelect);
+            }
+        });
     }
 
     /** This tab should be in a DockPane, not a plain TabPane
@@ -593,20 +604,24 @@ public void select()
      */
     public void addCloseCheck(final Supplier<Future<Boolean>> ok_to_close)
     {
-        if (getOnCloseRequest() == null)
-            setOnCloseRequest(event ->
-            {
-                // For now, prevent closing
-                event.consume();
+        var alreadyExistingEventHandler = getOnCloseRequest();
 
-                // Invoke all the ok-to-close checks in background threads
-                // since those that save files might take time.
-                JobManager.schedule("Close " + getLabel(), monitor ->
-                {
-                    if (prepareToClose())
-                        Platform.runLater(() -> close());
-                });
+        setOnCloseRequest(event -> {
+            // For now, prevent closing
+            event.consume();
+
+            // Invoke all the ok-to-close checks in background threads
+            // since those that save files might take time.
+            JobManager.schedule("Close " + getLabel(), monitor ->
+            {
+                if (prepareToClose()) {
+                    if (alreadyExistingEventHandler != null) {
+                        alreadyExistingEventHandler.handle(event);
+                    }
+                    Platform.runLater(() -> close());
+                }
             });
+        });
 
         close_check.add(ok_to_close);
     }
@@ -691,6 +706,10 @@ protected void handleClosed()
         setContent(null);
         // Remove "application" entry which otherwise holds on to application data model
         getProperties().remove(KEY_APPLICATION);
+        var dockPane = getDockPane();
+        if (dockPane != null) {
+            dockPane.tabsInOrderOfFocus.remove(this);
+        }
     }
 
     /** Programmatically close this tab

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

@@ -9,7 +9,11 @@
 
 import java.lang.ref.WeakReference;
 import java.text.MessageFormat;
-import java.util.*;
+import java.util.ArrayList;
+import java.util.Deque;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Objects;
 import java.util.concurrent.CopyOnWriteArrayList;
 import java.util.function.Consumer;
 import java.util.logging.Level;
@@ -219,8 +223,17 @@ public static void alwaysShowTabs(final boolean do_show_single_tabs)
         getTabs().addListener((InvalidationListener) change -> handleTabChanges());
 
         setOnContextMenuRequested(this::showContextMenu);
+
+        getSelectionModel().selectedItemProperty().addListener((observable, previous_item, new_item) -> {
+            // Keep track of the order of focus of tabs:
+            if (new_item != null) {
+                tabsInOrderOfFocus.remove(new_item);
+                tabsInOrderOfFocus.push((DockItem) new_item);
+            }
+        });
     }
 
+    protected LinkedList<DockItem> tabsInOrderOfFocus = new LinkedList<>();
 
     private void showContextMenu(final ContextMenuEvent event)
     {