From 8f48abba0227728d820861b1c167b0f566320d85 Mon Sep 17 00:00:00 2001
From: Oliver-Loeffler <Oliver-Loeffler@users.noreply.github.com>
Date: Mon, 3 Oct 2022 00:32:30 +0200
Subject: [PATCH] fix: Allows Scene Builder conditionally to load FXML files
 with unresolved imports.

There is also a new option (preserve unresolved imports) which also
allows to keep the imports in saved FXML files.
---
 .../app/DocumentWindowController.java         |  9 ++-
 .../preferences/PreferencesRecordGlobal.java  | 17 +++++-
 .../PreferencesWindowController.java          | 18 +++++-
 .../app/i18n/SceneBuilderApp.properties       |  1 +
 .../app/preferences/Preferences.fxml          | 61 +++++++++++--------
 .../kit/editor/EditorController.java          | 12 ++--
 .../scenebuilder/kit/fxom/FXOMDocument.java   | 36 +++++++++--
 .../scenebuilder/kit/fxom/FXOMLoader.java     | 34 ++++++++++-
 .../scenebuilder/kit/fxom/FXOMSaver.java      | 11 +++-
 .../kit/fxom/glue/GlueInstruction.java        |  5 ++
 .../PreferencesControllerBase.java            |  3 +-
 11 files changed, 164 insertions(+), 43 deletions(-)

diff --git a/app/src/main/java/com/oracle/javafx/scenebuilder/app/DocumentWindowController.java b/app/src/main/java/com/oracle/javafx/scenebuilder/app/DocumentWindowController.java
index 46668a048..74ad1d104 100644
--- a/app/src/main/java/com/oracle/javafx/scenebuilder/app/DocumentWindowController.java
+++ b/app/src/main/java/com/oracle/javafx/scenebuilder/app/DocumentWindowController.java
@@ -67,6 +67,7 @@
 import com.oracle.javafx.scenebuilder.kit.editor.selection.AbstractSelectionGroup;
 import com.oracle.javafx.scenebuilder.kit.editor.selection.ObjectSelectionGroup;
 import com.oracle.javafx.scenebuilder.kit.fxom.FXOMDocument;
+import com.oracle.javafx.scenebuilder.kit.fxom.FXOMDocument.FXOMDocumentSwitch;
 import com.oracle.javafx.scenebuilder.kit.fxom.FXOMNodes;
 import com.oracle.javafx.scenebuilder.kit.fxom.FXOMObject;
 import com.oracle.javafx.scenebuilder.kit.library.Library;
@@ -395,7 +396,13 @@ public SplitController getDocumentSplitController() {
     public void loadFromFile(File fxmlFile) throws IOException {
         final URL fxmlURL = fxmlFile.toURI().toURL();
         final String fxmlText = FXOMDocument.readContentFromURL(fxmlURL);
-        editorController.setFxmlTextAndLocation(fxmlText, fxmlURL, false);
+
+        FXOMDocumentSwitch[] options = PreferencesController.getSingleton().getRecordGlobal()
+                                                            .isPreserveUnresolvedImports() 
+                                                            ? new FXOMDocumentSwitch[] {FXOMDocumentSwitch.PRESERVE_UNRESOLVED_IMPORTS} 
+                                                            : new FXOMDocumentSwitch[0];
+
+        editorController.setFxmlTextAndLocation(fxmlText, fxmlURL, false, options);
         updateLoadFileTime();
         updateStageTitle(); // No-op if fxml has not been loaded yet
         updateFromDocumentPreferences(true);
diff --git a/app/src/main/java/com/oracle/javafx/scenebuilder/app/preferences/PreferencesRecordGlobal.java b/app/src/main/java/com/oracle/javafx/scenebuilder/app/preferences/PreferencesRecordGlobal.java
index c5c2fce3f..c8155efad 100644
--- a/app/src/main/java/com/oracle/javafx/scenebuilder/app/preferences/PreferencesRecordGlobal.java
+++ b/app/src/main/java/com/oracle/javafx/scenebuilder/app/preferences/PreferencesRecordGlobal.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2016, 2019, Gluon and/or its affiliates.
+ * Copyright (c) 2016, 2022, Gluon and/or its affiliates.
  * Copyright (c) 2012, 2014, Oracle and/or its affiliates.
  * All rights reserved. Use is subject to license terms.
  *
@@ -98,6 +98,7 @@ public String toString() {
     static final int DEFAULT_RECENT_ITEMS_SIZE = 15;
     static final boolean DEFAULT_ACCORDION_ANIMATION = true;
     static final boolean DEFAULT_WILDCARD_IMPORTS = false;
+    static final boolean DEFAULT_PRESERVE_UNRESOLVED_IMPORTS = true;
 
     /***************************************************************************
      *                                                                         *
@@ -113,6 +114,7 @@ public String toString() {
     private int recentItemsSize = DEFAULT_RECENT_ITEMS_SIZE;
     private boolean accordionAnimation = DEFAULT_ACCORDION_ANIMATION;
     private boolean wildcardImports = DEFAULT_WILDCARD_IMPORTS;
+    private boolean preserveUnresolvedImports = DEFAULT_PRESERVE_UNRESOLVED_IMPORTS;
     private final List<String> recentItems = new ArrayList<>();
 
     private LocalDate showUpdateDialogDate = null;
@@ -382,6 +384,14 @@ public void setWildcardImports(boolean wildcardImports) {
         this.wildcardImports = wildcardImports;
     }
 
+    public boolean isPreserveUnresolvedImports() {
+        return this.preserveUnresolvedImports;
+    }
+
+    public void setPreserveUnresolvedImports(boolean preserveUnresolvedImports) {
+        this.preserveUnresolvedImports = preserveUnresolvedImports;
+    }
+
     /**
      * Read data from the java preferences DB and initialize properties.
      */
@@ -468,7 +478,7 @@ public void readFromJavaPreferences() {
 
         // Wildcard imports
         setWildcardImports(applicationRootPreferences.getBoolean(WILDCARD_IMPORT, DEFAULT_WILDCARD_IMPORTS));
-
+        setPreserveUnresolvedImports(applicationRootPreferences.getBoolean(PRESERVE_UNRESOLVED_IMPORTS, DEFAULT_PRESERVE_UNRESOLVED_IMPORTS));
     }
 
     public void writeToJavaPreferences(String key) {
@@ -535,6 +545,9 @@ public void writeToJavaPreferences(String key) {
             case WILDCARD_IMPORT:
                 applicationRootPreferences.putBoolean(WILDCARD_IMPORT, isWildcardImports());
                 break;
+            case PRESERVE_UNRESOLVED_IMPORTS:
+                applicationRootPreferences.putBoolean(PRESERVE_UNRESOLVED_IMPORTS, isPreserveUnresolvedImports());
+                break;
             default:
                 super.writeToJavaPreferences(key);
                 break;
diff --git a/app/src/main/java/com/oracle/javafx/scenebuilder/app/preferences/PreferencesWindowController.java b/app/src/main/java/com/oracle/javafx/scenebuilder/app/preferences/PreferencesWindowController.java
index fb7564e5f..b45aec5ca 100644
--- a/app/src/main/java/com/oracle/javafx/scenebuilder/app/preferences/PreferencesWindowController.java
+++ b/app/src/main/java/com/oracle/javafx/scenebuilder/app/preferences/PreferencesWindowController.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2016, 2019, Gluon and/or its affiliates.
+ * Copyright (c) 2016, 2022, Gluon and/or its affiliates.
  * Copyright (c) 2012, 2014, Oracle and/or its affiliates.
  * All rights reserved. Use is subject to license terms.
  *
@@ -53,6 +53,7 @@
 import static com.oracle.javafx.scenebuilder.app.preferences.PreferencesController.RECENT_ITEMS_SIZE;
 import static com.oracle.javafx.scenebuilder.app.preferences.PreferencesController.TOOL_THEME;
 import static com.oracle.javafx.scenebuilder.app.preferences.PreferencesController.WILDCARD_IMPORT;
+import static com.oracle.javafx.scenebuilder.app.preferences.PreferencesController.PRESERVE_UNRESOLVED_IMPORTS;
 
 import static com.oracle.javafx.scenebuilder.kit.preferences.PreferencesRecordGlobalBase.DEFAULT_ALIGNMENT_GUIDES_COLOR;
 import static com.oracle.javafx.scenebuilder.kit.preferences.PreferencesRecordGlobalBase.DEFAULT_BACKGROUND_IMAGE;
@@ -139,6 +140,8 @@ public class PreferencesWindowController extends AbstractFxmlWindowController {
     private CheckBox animateAccordion;
     @FXML
     private CheckBox wildcardImports;
+    @FXML
+    private CheckBox preserveUnresolvedImports;
 
     private PaintPicker alignmentColorPicker;
     private PaintPicker parentRingColorPicker;
@@ -259,6 +262,9 @@ protected void controllerDidLoadFxml() {
         // Wildcard Imports
         wildcardImports.setSelected(recordGlobal.isWildcardImports());
         wildcardImports.selectedProperty().addListener(new WildcardImportListener());
+        
+        preserveUnresolvedImports.setSelected(recordGlobal.isPreserveUnresolvedImports());
+        preserveUnresolvedImports.selectedProperty().addListener(new PreserveUnresolvedImportListener());
     }
 
     /*
@@ -576,4 +582,14 @@ public void changed(ObservableValue<? extends Boolean> observable, Boolean oldVa
             recordGlobal.writeToJavaPreferences(WILDCARD_IMPORT);
         }
     }
+
+    private static class PreserveUnresolvedImportListener implements ChangeListener<Boolean> {
+        @Override
+        public void changed(ObservableValue<? extends Boolean> observable, Boolean oldValue, Boolean newValue) {
+            final PreferencesController preferencesController = PreferencesController.getSingleton();
+            final PreferencesRecordGlobal recordGlobal = preferencesController.getRecordGlobal();
+            recordGlobal.setPreserveUnresolvedImports(newValue);
+            recordGlobal.writeToJavaPreferences(PRESERVE_UNRESOLVED_IMPORTS);
+        }
+    }
 }
diff --git a/app/src/main/resources/com/oracle/javafx/scenebuilder/app/i18n/SceneBuilderApp.properties b/app/src/main/resources/com/oracle/javafx/scenebuilder/app/i18n/SceneBuilderApp.properties
index 761a6db8d..aab0c718d 100644
--- a/app/src/main/resources/com/oracle/javafx/scenebuilder/app/i18n/SceneBuilderApp.properties
+++ b/app/src/main/resources/com/oracle/javafx/scenebuilder/app/i18n/SceneBuilderApp.properties
@@ -249,6 +249,7 @@ prefs.cssanalyzer.columns.defaults.last = "Defaults" Column Last
 prefs.recent.items = Recent items :
 prefs.animate.accordion = Animate Accordion :
 prefs.wildcard.import = Use Wildcard Imports :
+prefs.preserve.unresolved.import = Keep unresolved imports :
 prefs.reset.default = Reset to Builtin Default Values
 prefs.document.theme = Default Theme :
 prefs.document.gluonswatch = Default Gluon Swatch :
diff --git a/app/src/main/resources/com/oracle/javafx/scenebuilder/app/preferences/Preferences.fxml b/app/src/main/resources/com/oracle/javafx/scenebuilder/app/preferences/Preferences.fxml
index e9b02f042..0129a30e8 100644
--- a/app/src/main/resources/com/oracle/javafx/scenebuilder/app/preferences/Preferences.fxml
+++ b/app/src/main/resources/com/oracle/javafx/scenebuilder/app/preferences/Preferences.fxml
@@ -37,19 +37,19 @@
 <?import java.lang.String?>
 <?import javafx.collections.FXCollections?>
 <?import javafx.geometry.Insets?>
-<?import javafx.scene.control.Label?>
-<?import javafx.scene.control.Separator?>
+<?import javafx.scene.control.Button?>
+<?import javafx.scene.control.CheckBox?>
 <?import javafx.scene.control.ChoiceBox?>
-<?import javafx.scene.control.MenuButton?>
 <?import javafx.scene.control.CustomMenuItem?>
-<?import javafx.scene.control.CheckBox?>
-<?import javafx.scene.control.Button?>
+<?import javafx.scene.control.Label?>
+<?import javafx.scene.control.MenuButton?>
+<?import javafx.scene.control.Separator?>
 <?import javafx.scene.layout.ColumnConstraints?>
-<?import javafx.scene.layout.RowConstraints?>
 <?import javafx.scene.layout.GridPane?>
+<?import javafx.scene.layout.RowConstraints?>
 <?import javafx.scene.shape.Rectangle?>
 
-<GridPane hgap="6.0" maxWidth="1.7976931348623157E308" styleClass="theme-presets" vgap="10.0" xmlns="http://javafx.com/javafx/8" xmlns:fx="http://javafx.com/fxml/1">
+<GridPane hgap="6.0" maxWidth="1.7976931348623157E308" styleClass="theme-presets" vgap="10.0" xmlns="http://javafx.com/javafx/19" xmlns:fx="http://javafx.com/fxml/1">
   <children>
     <Label text="%prefs.doc.width" GridPane.columnIndex="0" GridPane.rowIndex="0" />
     <DoubleField fx:id="rootContainerWidth" prefWidth="200.0" text="" GridPane.columnIndex="1" GridPane.rowIndex="0" />
@@ -121,14 +121,16 @@
     <Separator prefWidth="-1.0" GridPane.columnIndex="0" GridPane.columnSpan="2" GridPane.rowIndex="16" />
 
     <Label text="%prefs.animate.accordion" GridPane.columnIndex="0" GridPane.rowIndex="17" />
-    <CheckBox fx:id="animateAccordion" selected="true" GridPane.columnIndex="1" GridPane.rowIndex="17"/>
+    <CheckBox fx:id="animateAccordion" selected="true" GridPane.columnIndex="1" GridPane.rowIndex="17" />
 
     <Label text="%prefs.wildcard.import" GridPane.columnIndex="0" GridPane.rowIndex="18" />
-    <CheckBox fx:id="wildcardImports" selected="true" GridPane.columnIndex="1" GridPane.rowIndex="18"/>
+    <CheckBox fx:id="wildcardImports" selected="true" GridPane.columnIndex="1" GridPane.rowIndex="18" />
 
-    <Separator prefWidth="-1.0" GridPane.columnIndex="0" GridPane.columnSpan="2" GridPane.rowIndex="19" />
+    <Separator prefWidth="-1.0" GridPane.columnIndex="0" GridPane.columnSpan="2" GridPane.rowIndex="20" />
 
-    <Button onAction="#resetToDefaultAction" prefWidth="-1.0" text="%prefs.reset.default" GridPane.columnIndex="0" GridPane.columnSpan="2" GridPane.halignment="CENTER" GridPane.rowIndex="20" />
+    <Button onAction="#resetToDefaultAction" prefWidth="-1.0" text="%prefs.reset.default" GridPane.columnIndex="0" GridPane.columnSpan="2" GridPane.halignment="CENTER" GridPane.rowIndex="21" />
+      <Label text="%prefs.preserve.unresolved.import" GridPane.rowIndex="19" />
+      <CheckBox fx:id="preserveUnresolvedImports" selected="true" GridPane.columnIndex="1" GridPane.rowIndex="19" />
   </children>
   <columnConstraints>
     <ColumnConstraints halignment="RIGHT" hgrow="SOMETIMES" maxWidth="-Infinity" minWidth="-Infinity" />
@@ -138,20 +140,27 @@
     <Insets bottom="20.0" left="20.0" right="20.0" top="20.0" />
   </padding>
   <rowConstraints>
-    <RowConstraints maxHeight="-Infinity" minHeight="-Infinity" prefHeight="-1.0" vgrow="NEVER" />
-    <RowConstraints maxHeight="-Infinity" minHeight="-Infinity" prefHeight="-1.0" vgrow="NEVER" />
-    <RowConstraints maxHeight="-Infinity" minHeight="-Infinity" prefHeight="-1.0" vgrow="NEVER" />
-    <RowConstraints maxHeight="-Infinity" minHeight="-Infinity" prefHeight="-1.0" vgrow="NEVER" />
-    <RowConstraints maxHeight="-Infinity" minHeight="-Infinity" prefHeight="-1.0" vgrow="NEVER" />
-    <RowConstraints maxHeight="-Infinity" minHeight="-Infinity" prefHeight="-1.0" vgrow="NEVER" />
-    <RowConstraints maxHeight="-Infinity" minHeight="-Infinity" prefHeight="-1.0" vgrow="NEVER" />
-    <RowConstraints maxHeight="-Infinity" minHeight="-Infinity" prefHeight="-1.0" vgrow="NEVER" />
-    <RowConstraints maxHeight="-Infinity" minHeight="-Infinity" prefHeight="-1.0" vgrow="NEVER" />
-    <RowConstraints maxHeight="-Infinity" minHeight="-Infinity" prefHeight="-1.0" vgrow="NEVER" />
-    <RowConstraints maxHeight="-Infinity" minHeight="-Infinity" prefHeight="-1.0" vgrow="NEVER" />
-    <RowConstraints maxHeight="-Infinity" minHeight="-Infinity" prefHeight="-1.0" vgrow="NEVER" />
-    <RowConstraints maxHeight="-Infinity" minHeight="-Infinity" prefHeight="-1.0" vgrow="NEVER" />
-    <RowConstraints maxHeight="-Infinity" minHeight="-Infinity" prefHeight="-1.0" vgrow="NEVER" />
-    <RowConstraints maxHeight="-Infinity" minHeight="-Infinity" prefHeight="-1.0" vgrow="NEVER" />
+    <RowConstraints maxHeight="-Infinity" minHeight="-Infinity" vgrow="NEVER" />
+    <RowConstraints maxHeight="-Infinity" minHeight="-Infinity" vgrow="NEVER" />
+    <RowConstraints maxHeight="-Infinity" minHeight="-Infinity" vgrow="NEVER" />
+    <RowConstraints maxHeight="-Infinity" minHeight="-Infinity" vgrow="NEVER" />
+    <RowConstraints maxHeight="-Infinity" minHeight="-Infinity" vgrow="NEVER" />
+    <RowConstraints maxHeight="-Infinity" minHeight="-Infinity" vgrow="NEVER" />
+    <RowConstraints maxHeight="-Infinity" minHeight="-Infinity" vgrow="NEVER" />
+    <RowConstraints maxHeight="-Infinity" minHeight="-Infinity" vgrow="NEVER" />
+    <RowConstraints maxHeight="-Infinity" minHeight="-Infinity" vgrow="NEVER" />
+    <RowConstraints maxHeight="-Infinity" minHeight="-Infinity" vgrow="NEVER" />
+    <RowConstraints maxHeight="-Infinity" minHeight="-Infinity" vgrow="NEVER" />
+    <RowConstraints maxHeight="-Infinity" minHeight="-Infinity" vgrow="NEVER" />
+    <RowConstraints maxHeight="-Infinity" minHeight="-Infinity" vgrow="NEVER" />
+    <RowConstraints maxHeight="-Infinity" minHeight="-Infinity" vgrow="NEVER" />
+    <RowConstraints maxHeight="-Infinity" minHeight="-Infinity" vgrow="NEVER" />
+      <RowConstraints />
+      <RowConstraints />
+      <RowConstraints />
+      <RowConstraints />
+      <RowConstraints />
+      <RowConstraints />
+      <RowConstraints />
   </rowConstraints>
 </GridPane>
diff --git a/kit/src/main/java/com/oracle/javafx/scenebuilder/kit/editor/EditorController.java b/kit/src/main/java/com/oracle/javafx/scenebuilder/kit/editor/EditorController.java
index 211152d1d..84f473482 100644
--- a/kit/src/main/java/com/oracle/javafx/scenebuilder/kit/editor/EditorController.java
+++ b/kit/src/main/java/com/oracle/javafx/scenebuilder/kit/editor/EditorController.java
@@ -103,6 +103,7 @@
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
+import java.util.EnumSet;
 import java.util.HashSet;
 import java.util.List;
 import java.util.ResourceBundle;
@@ -758,10 +759,11 @@ public void setFxmlTextAndLocation(String fxmlText, URL fxmlLocation) throws IOE
      * @param fxmlLocation null or the location of the fxml text being edited
      * @param checkTheme if set to true a check will be made if the fxml contains
      *                           Gluon controls and if so, the correct theme is set
+     * @param switches Optional switches to configure FXOM and FXML processes
      * @throws IOException if fxml text cannot be parsed and loaded correctly.
      */
-    public void setFxmlTextAndLocation(String fxmlText, URL fxmlLocation, boolean checkTheme) throws IOException {
-        updateFxomDocument(fxmlText, fxmlLocation, getResources(), checkTheme);
+    public void setFxmlTextAndLocation(String fxmlText, URL fxmlLocation, boolean checkTheme, FXOMDocumentSwitch ... switches) throws IOException {
+        updateFxomDocument(fxmlText, fxmlLocation, getResources(), checkTheme, switches);
         this.fxmlLocationProperty.setValue(fxmlLocation);
     }
 
@@ -2554,11 +2556,13 @@ private boolean isSelectionControl() {
         return true;
     }
 
-    private void updateFxomDocument(String fxmlText, URL fxmlLocation, ResourceBundle resources, boolean checkTheme) throws IOException {
+    private void updateFxomDocument(String fxmlText, URL fxmlLocation, ResourceBundle resources, boolean checkTheme, FXOMDocumentSwitch ... switches) throws IOException {
         final FXOMDocument newFxomDocument;
         
         if (fxmlText != null) {
-            newFxomDocument = new FXOMDocument(fxmlText, fxmlLocation, getLibrary().getClassLoader(), resources, FXOMDocumentSwitch.NORMALIZED);
+            Set<FXOMDocumentSwitch> options = EnumSet.of(FXOMDocumentSwitch.NORMALIZED);
+            options.addAll(Set.of(switches));
+            newFxomDocument = new FXOMDocument(fxmlText, fxmlLocation, getLibrary().getClassLoader(), resources, options.toArray(new FXOMDocumentSwitch[0]));
         } else {
             newFxomDocument = null;
         }
diff --git a/kit/src/main/java/com/oracle/javafx/scenebuilder/kit/fxom/FXOMDocument.java b/kit/src/main/java/com/oracle/javafx/scenebuilder/kit/fxom/FXOMDocument.java
index 5a8bd248d..68389d216 100644
--- a/kit/src/main/java/com/oracle/javafx/scenebuilder/kit/fxom/FXOMDocument.java
+++ b/kit/src/main/java/com/oracle/javafx/scenebuilder/kit/fxom/FXOMDocument.java
@@ -50,6 +50,7 @@
 
 import javafx.beans.property.ReadOnlyIntegerProperty;
 import javafx.beans.property.SimpleIntegerProperty;
+import javafx.fxml.FXMLLoader;
 import javafx.scene.Node;
 
 import com.oracle.javafx.scenebuilder.kit.fxom.glue.GlueDocument;
@@ -77,6 +78,7 @@ public class FXOMDocument {
     private final SimpleIntegerProperty cssRevision = new SimpleIntegerProperty();
     private SceneGraphHolder sceneGraphHolder;
     private int updateDepth;
+    private List<String> missingClasses = new ArrayList<>();
 
     private boolean hasGluonControls;
     
@@ -112,7 +114,7 @@ public FXOMDocument(String fxmlText, URL location, ClassLoader classLoader, Reso
                 fxmlTextToLoad = fxmlPropertiesDisabler.disableProperties(fxmlText);
             }
             final FXOMLoader loader = new FXOMLoader(this);
-            loader.load(fxmlTextToLoad);
+            loader.load(fxmlTextToLoad, switches);
             if (availableSwitches.contains(FXOMDocumentSwitch.NORMALIZED)) {
                 final FXOMNormalizer normalizer = new FXOMNormalizer(this);
                 normalizer.normalize();
@@ -126,6 +128,24 @@ public FXOMDocument(String fxmlText, URL location, ClassLoader classLoader, Reso
 
         hasGluonControls = fxmlText.contains(EditorPlatform.GLUON_PACKAGE);
     }
+
+    /**
+     * Adds the name of a class or a name space which could not be resolved by FXMLLoader.
+     * 
+     * @param missingClassName Either a class namr from an import or a name space from a wild card import.
+     */
+    public void addMissingClass(String missingClassName) {
+        this.missingClasses.add(missingClassName);
+    }
+
+    /**
+     * If there were unresolved FXML import statements, affected class names and package name spaces are provided here.
+     * 
+     * @return list of unresolved FXML import class names or name spaces.
+     */
+    public List<String> getMissingClasses() {
+        return this.missingClasses;
+    }
         
     public FXOMDocument() {
         this.glue = new GlueDocument();
@@ -159,7 +179,7 @@ public void setClassLoader(ClassLoader classLoader) {
         this.classLoader = classLoader;
         endUpdate();
     }    
-    
+
     public List<Class<?>> getInitialDeclaredClasses() {
         return initialDeclaredClasses;
     }
@@ -201,8 +221,8 @@ public void setSampleDataEnabled(boolean sampleDataEnabled) {
                 sampleDataGenerator.assignSampleData(fxomRoot);
             }
         }
-    }    
-    
+    }
+
     public FXOMObject getFxomRoot() {
         return fxomRoot;
     }
@@ -480,6 +500,12 @@ public enum FXOMDocumentSwitch {
          * configuration. One possible example here is the option to use the MacOS
          * system menu bar.
          */
-        FOR_PREVIEW;
+        FOR_PREVIEW,
+        
+        /**
+         * This flag ensures that the {@link FXOMLoader} preserves imports which were not resolvable by {@link FXMLLoader}.
+         * This behavior is controlled using Preferences-API.
+         */
+        PRESERVE_UNRESOLVED_IMPORTS;
     }
 }
diff --git a/kit/src/main/java/com/oracle/javafx/scenebuilder/kit/fxom/FXOMLoader.java b/kit/src/main/java/com/oracle/javafx/scenebuilder/kit/fxom/FXOMLoader.java
index 0fa6dcaf7..705c9ad9d 100644
--- a/kit/src/main/java/com/oracle/javafx/scenebuilder/kit/fxom/FXOMLoader.java
+++ b/kit/src/main/java/com/oracle/javafx/scenebuilder/kit/fxom/FXOMLoader.java
@@ -34,6 +34,7 @@
 
 import com.oracle.javafx.scenebuilder.kit.i18n.I18N;
 import com.oracle.javafx.scenebuilder.kit.editor.panel.util.dialog.ErrorDialog;
+import com.oracle.javafx.scenebuilder.kit.fxom.FXOMDocument.FXOMDocumentSwitch;
 import com.oracle.javafx.scenebuilder.kit.metadata.util.PropertyName;
 import com.oracle.javafx.scenebuilder.kit.util.Deprecation;
 import javafx.fxml.LoadListener;
@@ -47,9 +48,13 @@
 import java.io.IOException;
 import java.io.InputStream;
 import java.nio.charset.Charset;
+import java.util.ArrayList;
 import java.util.Collections;
+import java.util.List;
 import java.util.Objects;
+import java.util.Set;
 import java.util.function.Consumer;
+import java.util.stream.Collectors;
 
 
 /**
@@ -78,7 +83,7 @@ public FXOMLoader(FXOMDocument document) {
         this.knownErrorsHandler = Objects.requireNonNull(knownErrorsHandler);
     }
 
-    public void load(String fxmlText) throws java.io.IOException {
+    public void load(String fxmlText, FXOMDocumentSwitch ... switches) throws java.io.IOException {
         assert fxmlText != null;
 
         final ClassLoader classLoader;
@@ -103,8 +108,33 @@ public void load(String fxmlText) throws java.io.IOException {
             is.reset();
             setSceneGraphRoot(fxmlLoader.load(is));
         } catch (RuntimeException | IOException x) {
-            handleFxmlLoadingError(x);
+            Throwable cause = x.getCause();
+            if (cause instanceof ClassNotFoundException missingClass 
+                && Set.of(switches).contains(FXOMDocumentSwitch.PRESERVE_UNRESOLVED_IMPORTS)) {
+                String message = missingClass.getMessage();
+                String modifiedFxml = removeMissingClassesImports(fxmlText, message);
+                load(modifiedFxml, switches);
+            } else {                
+                handleFxmlLoadingError(x);
+            }
+        }
+    }
+
+    
+
+    private String removeMissingClassesImports(String fxmlText, String missingClass) {
+        List<String> lines = new ArrayList<>(fxmlText.lines().toList());
+        for (int i = 0; i < lines.size(); i++) {
+            if (lines.get(i).matches("^\s?[<]\s?[?]\s?import\s?.*")) {
+                    if (lines.get(i).contains(missingClass)) {
+                        document.addMissingClass(missingClass);
+                        lines.set(i, "");
+                        break;
+                    }
+            }
         }
+        return lines.stream()
+                    .collect(Collectors.joining(System.lineSeparator()));
     }
 
     private void handleFxmlLoadingError(Exception x) throws IOException {
diff --git a/kit/src/main/java/com/oracle/javafx/scenebuilder/kit/fxom/FXOMSaver.java b/kit/src/main/java/com/oracle/javafx/scenebuilder/kit/fxom/FXOMSaver.java
index c478333a9..ad5aa3bb9 100644
--- a/kit/src/main/java/com/oracle/javafx/scenebuilder/kit/fxom/FXOMSaver.java
+++ b/kit/src/main/java/com/oracle/javafx/scenebuilder/kit/fxom/FXOMSaver.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2016, 2019, Gluon and/or its affiliates.
+ * Copyright (c) 2016, 2022, Gluon and/or its affiliates.
  * Copyright (c) 2012, 2014, Oracle and/or its affiliates.
  * All rights reserved. Use is subject to license terms.
  *
@@ -114,6 +114,9 @@ private void updateImportInstructions(FXOMDocument fxomDocument) {
         // gets list of the imports to be added to the FXML document.
         List<GlueInstruction> importList = getHeaderIncludes(fxomDocument);
 
+        List<GlueInstruction> missingImports = getMissingClassesImports(fxomDocument);;
+        importList.addAll(missingImports);
+
         // synchronizes the glue with the list of glue instructions
         synchronizeHeader(fxomDocument.getGlue(), importList);
     }
@@ -136,6 +139,12 @@ private List<GlueInstruction> getHeaderIncludes(FXOMDocument fxomDocument) {
 
         return createGlueInstructionsForImports(fxomDocument, imports);
     }
+    
+    private List<GlueInstruction> getMissingClassesImports(FXOMDocument fxomDocument) {
+        final Set<String> imports = new TreeSet<>(); // Sorted
+        imports.addAll(fxomDocument.getMissingClasses());
+        return createGlueInstructionsForImports(fxomDocument, imports);
+    }
 
     private Set<String> findPropertyClasses(FXOMObject... fxomObjects) {
         return Arrays.stream(fxomObjects)
diff --git a/kit/src/main/java/com/oracle/javafx/scenebuilder/kit/fxom/glue/GlueInstruction.java b/kit/src/main/java/com/oracle/javafx/scenebuilder/kit/fxom/glue/GlueInstruction.java
index 6a10c801b..7b30a9490 100644
--- a/kit/src/main/java/com/oracle/javafx/scenebuilder/kit/fxom/glue/GlueInstruction.java
+++ b/kit/src/main/java/com/oracle/javafx/scenebuilder/kit/fxom/glue/GlueInstruction.java
@@ -1,4 +1,5 @@
 /*
+ * Copyright (c) 2017, 2022, Gluon and/or its affiliates.
  * Copyright (c) 2012, 2014, Oracle and/or its affiliates.
  * All rights reserved. Use is subject to license terms.
  *
@@ -54,5 +55,9 @@ public String getData() {
         return data;
     }
     
+    @Override
+    public String toString() {
+        return "GlueInstruction: %s : %s".formatted(String.valueOf(target), String.valueOf(data));
+    }
 
 }
diff --git a/kit/src/main/java/com/oracle/javafx/scenebuilder/kit/preferences/PreferencesControllerBase.java b/kit/src/main/java/com/oracle/javafx/scenebuilder/kit/preferences/PreferencesControllerBase.java
index 9ad3e3a2f..5e966ba60 100644
--- a/kit/src/main/java/com/oracle/javafx/scenebuilder/kit/preferences/PreferencesControllerBase.java
+++ b/kit/src/main/java/com/oracle/javafx/scenebuilder/kit/preferences/PreferencesControllerBase.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2017, 2019, Gluon and/or its affiliates.
+ * Copyright (c) 2017, 2022, Gluon and/or its affiliates.
  * All rights reserved. Use is subject to license terms.
  *
  * This file is available and licensed under the following license:
@@ -62,6 +62,7 @@ public abstract class PreferencesControllerBase {
     public static final String HIERARCHY_DISPLAY_OPTION = "HIERARCHY_DISPLAY_OPTION"; //NOI18N
     public static final String ACCORDION_ANIMATION = "ACCORDION_ANIMATION"; //NOI18N
     public static final String WILDCARD_IMPORT = "WILDCARD_IMPORT"; //NOI18N
+    public static final String PRESERVE_UNRESOLVED_IMPORTS = "PRESERVE_UNRESOLVED_IMPORTS"; //NOI18N
 
     // DOCUMENT SPECIFIC PREFERENCES
     public static final String PATH = "path"; //NOI18N