Revert "CSSTUDIO-1987 Remove unused code."

app/display/runtime/src/main/java/org/csstudio/display/builder/runtime/app/DockItemRepresentation.java

@@ -141,4 +141,24 @@ public void representModel(final Parent model_parent, final DisplayModel model)
             app_instance.trackCurrentModel(model);
         super.representModel(model_parent, model);
     }
+
+    @Override
+    public void closeWindow(final DisplayModel model) throws Exception
+    {
+        // Is called from ScriptUtil, i.e. scripts, from background thread
+        final Parent model_parent = Objects.requireNonNull(model.getUserData(Widget.USER_DATA_TOOLKIT_PARENT));
+        if (model_parent.getProperties().get(DisplayRuntimeInstance.MODEL_PARENT_DISPLAY_RUNTIME) == app_instance)
+        {
+            // Prepare-to-close, which might take time and must be called off the UI thread
+            final DisplayRuntimeInstance instance = (DisplayRuntimeInstance) app_instance.getRepresentation().getModelParent().getProperties().get(DisplayRuntimeInstance.MODEL_PARENT_DISPLAY_RUNTIME);
+            if (instance != null)
+                instance.getDockItem().prepareToClose();
+            else
+                logger.log(Level.SEVERE, "Missing DisplayRuntimeInstance to prepare closing", new Exception("Stack Trace"));
+            // 'close' on the UI thread
+            execute(() -> app_instance.close());
+        }
+        else
+            throw new Exception("Wrong model");
+    }
 }

app/display/runtime/src/main/java/org/csstudio/display/builder/runtime/script/ScriptUtil.java

@@ -141,6 +141,24 @@ public static void openDisplay(final Widget widget, final String file, final Str
         ActionUtil.handleAction(widget, open);
     }
 
+    /** Close a display
+     *
+     *  @param widget Widget within the display to close
+     */
+    public static void closeDisplay(final Widget widget)
+    {
+        try
+        {
+            final DisplayModel model = widget.getTopDisplayModel();
+            final ToolkitRepresentation<Object, Object> toolkit = ToolkitRepresentation.getToolkit(model);
+            toolkit.closeWindow(model);
+        }
+        catch (Throwable ex)
+        {
+            logger.log(Level.WARNING, "Cannot close display", ex);
+        }
+    }
+
     // ====================
     // public alert dialog utils