diff --git a/README.md b/README.md
index 62e56b1..0949a81 100644
--- a/README.md
+++ b/README.md
@@ -166,18 +166,21 @@ Strictly, the constructor of `SourceCodeViewer` receives a map with arbitrary va
 This feature supports highlighting a source code fragment in order to emphasize a section of the code snippet.
 The highlighted fragment is automatically scrolled into view.
 
-A fragment is highlighted either by calling `SourceCodeViewer.highlight(name)` or when hovering a component that has been configured with `SourceCodeViewer.highlightOnHover(component,name)`, where `name` is the name of the fragment. `SourceCodeViewer.highlight(null)` turn off the highlighting.
-`SourceCodeViewer.highlightOnClick` allows configuring a click listener that turns highlight on.
+A fragment is highlighted either by calling `SourceCodeViewer.highlight(filenameAndId)` or when clicking/hovering a component that has been configured with `SourceCodeViewer.highlightOnClick` or `SourceCodeViewer.highlightOnHover`, where `filenameAndId` is the name of the fragment. If the component is in an additional source file, `filenameAndId` can be given as a string in the format `filename#id`. If no `'#'` is present, it is assumed that the identifier corresponds to a block in the first source panel. `SourceCodeViewer.highlight(null)` turns off the highlighting.
 
-In the source code, a fragment is delimited by `// begin-block name` and `// end-block` comments. Nested fragments are not supported.
+In the source code, a fragment is delimited by `// begin-block filenameAndId` and `// end-block` comments. Nested fragments are not supported.
 The `// begin-block` and `// end-block` comments are removed after post-processing.
 
 ```
     // begin-block first
-    Div first = new Div(new Text("First"));
+    Div first = new Div(new Text("Highlight block in first panel"));
     SourceCodeViewer.highlightOnHover(first, "first");
     add(first);
     // end-block
+    
+    Div other = new Div(new Text("Highlight additional source"));
+    SourceCodeViewer.highlightOnHover(other, "AdditionalSource.java#other");
+    add(other);
 ```
 
 <!-- FROM https://github.com/FlowingCode/CommonsDemo/pull/62 -->
diff --git a/src/main/java/com/flowingcode/vaadin/addons/demo/MultiSourceCodeViewer.java b/src/main/java/com/flowingcode/vaadin/addons/demo/MultiSourceCodeViewer.java
index eda3b6d..b2138c0 100644
--- a/src/main/java/com/flowingcode/vaadin/addons/demo/MultiSourceCodeViewer.java
+++ b/src/main/java/com/flowingcode/vaadin/addons/demo/MultiSourceCodeViewer.java
@@ -6,6 +6,7 @@
 import com.vaadin.flow.component.tabs.Tabs;
 import java.util.List;
 import java.util.Map;
+import java.util.Optional;
 
 public class MultiSourceCodeViewer extends Div {
 
@@ -15,13 +16,21 @@ public class MultiSourceCodeViewer extends Div {
 
   private SourceCodeViewer codeViewer;
   private Tab selectedTab;
+  private Tabs tabs;
 
   public MultiSourceCodeViewer(List<SourceCodeTab> sourceCodeTabs, Map<String, String> properties) {
     if (sourceCodeTabs.size() > 1) {
-      Tabs tabs = new Tabs(createTabs(sourceCodeTabs));
+      tabs = new Tabs(createTabs(sourceCodeTabs));
       tabs.addSelectedChangeListener(ev -> onTabSelected(ev.getSelectedTab()));
       add(tabs);
       selectedTab = tabs.getSelectedTab();
+
+      getElement().addEventListener("fragment-request", ev -> {
+        String filename = ev.getEventData().get("event.detail.filename").asString();
+        findTabWithFilename(filename).ifPresent(tab -> {
+          tabs.setSelectedTab(tab);
+        });
+      }).addEventData("event.detail.filename");
     } else {
       selectedTab = createTab(sourceCodeTabs.get(0));
     }
@@ -89,7 +98,7 @@ private String getExtension(String filename) {
   }
 
   private void onTabSelected(Tab tab) {
-    this.selectedTab = tab;
+    selectedTab = tab;
 
     String url = (String) ComponentUtil.getData(tab, DATA_URL);
     String language = (String) ComponentUtil.getData(tab, DATA_LANGUAGE);
@@ -104,4 +113,15 @@ public SourcePosition getSourcePosition() {
     return (SourcePosition) ComponentUtil.getData(selectedTab, DATA_POSITION);
   }
 
+  private Optional<Tab> findTabWithFilename(String filename) {
+    if (tabs != null) {
+      return tabs.getChildren().filter(Tab.class::isInstance).map(Tab.class::cast).filter(tab -> {
+        String url = (String) ComponentUtil.getData(tab, DATA_URL);
+        return filename == null || getFilename(url).equals(filename);
+      }).findFirst();
+    } else {
+      return Optional.empty();
+    }
+  }
+
 }
diff --git a/src/main/java/com/flowingcode/vaadin/addons/demo/SourceCodeViewer.java b/src/main/java/com/flowingcode/vaadin/addons/demo/SourceCodeViewer.java
index beb1786..300cceb 100644
--- a/src/main/java/com/flowingcode/vaadin/addons/demo/SourceCodeViewer.java
+++ b/src/main/java/com/flowingcode/vaadin/addons/demo/SourceCodeViewer.java
@@ -89,20 +89,54 @@ private void setProperties(Map<String, String> properties) {
     }
   }
 
-  public static void highlightOnHover(Component c, String id) {
+  /**
+   * Highlights the block identified by {@code filenameAndId} when the component is hovered over.
+   * <p>
+   * If the component is in an additional source, {@code filenameAndId} can be given as a string in
+   * the format {@code filename#id}. If no {@code '#'} is present, it is assumed that the identifier
+   * corresponds to a block in the first source panel.
+   *
+   * @param c The component that triggers the highlight action when hovered over.
+   * @param filenameAndId The identifier string that combines filename and id separated by
+   *        {@code '#'}.
+   */
+  public static void highlightOnHover(Component c, String filenameAndId) {
     c.addAttachListener(ev -> {
-      c.getElement().executeJs("Vaadin.Flow.fcCodeViewerConnector.highlightOnHover(this,$0)", id);
+      c.getElement().executeJs("Vaadin.Flow.fcCodeViewerConnector.highlightOnHover(this,$0)", filenameAndId);
     });
   }
 
-  public static <T extends HasElement & ClickNotifier<?>> void highlightOnClick(T c, String id) {
+  /**
+   * Highlight block {@code id} when the component is clicked.
+   * <p>
+   * If the component is in an additional source, {@code filenameAndId} can be given as a string in
+   * the format {@code filename#id}. If no {@code '#'} is present, it is assumed that the identifier
+   * corresponds to a block in the first source panel.
+   *
+   * @param c The component that triggers the highlight action when clicked.
+   * @param filenameAndId The identifier string that combines filename and id separated by
+   *        {@code '#'}.
+   */
+  public static <T extends HasElement & ClickNotifier<?>> void highlightOnClick(T c,
+      String filenameAndId) {
     c.addClickListener(ev -> {
-      c.getElement().executeJs("Vaadin.Flow.fcCodeViewerConnector.highlight($0)", id);
+      c.getElement().executeJs("Vaadin.Flow.fcCodeViewerConnector.highlight($0)", filenameAndId);
     });
   }
 
-  public static void highlight(String id) {
-    UI.getCurrent().getElement().executeJs("Vaadin.Flow.fcCodeViewerConnector.highlight($0)", id);
+  /**
+   * Highlights the block identified by {@code filenameAndId}.
+   * <p>
+   * If the component is in an additional source, {@code filenameAndId} can be given as a string in
+   * the format {@code filename#id}. If no {@code '#'} is present, it is assumed that the identifier
+   * corresponds to a block in the first source panel.
+   *
+   * @param filenameAndId The identifier string that combines filename and id separated by
+   *        {@code '#'}.
+   */
+
+  public static void highlight(String filenameAndId) {
+    UI.getCurrent().getElement().executeJs("Vaadin.Flow.fcCodeViewerConnector.highlight($0)", filenameAndId);
   }
 
 }
diff --git a/src/main/resources/META-INF/resources/frontend/code-viewer.ts b/src/main/resources/META-INF/resources/frontend/code-viewer.ts
index 9d71a75..44f1a72 100644
--- a/src/main/resources/META-INF/resources/frontend/code-viewer.ts
+++ b/src/main/resources/META-INF/resources/frontend/code-viewer.ts
@@ -2,7 +2,7 @@
  * #%L
  * Commons Demo
  * %%
- * Copyright (C) 2020 - 2023 Flowing Code
+ * Copyright (C) 2020 - 2024 Flowing Code
  * %%
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -51,6 +51,8 @@ export class CodeViewer extends LitElement {
 
   private __license : Element[] = [];
   
+  private __highlightedBlock : string | null = null;
+    
   env: any = {};
   
   createRenderRoot() {
@@ -234,6 +236,7 @@ pre[class*="language-"] {
       (window as any).Prism.highlightAllUnder(self);
       self.__license.reverse().forEach(e=>self.querySelector('pre code')?.prepend(e));
       self.process(code);
+      self._highlight(self.__highlightedBlock, false);
     }};
     xhr.open('GET', sourceUrl, true);
     xhr.send();
@@ -435,20 +438,35 @@ pre[class*="language-"] {
   }
   
   /** @deprecated Use highlight(id: string|null) instead */
-  highligth(id:string|null) {
-    this.highlight(id);
+  highligth(filenameAndId:string|null) {
+    this.highlight(filenameAndId);
   }
   
   //highlight a marked block
-  highlight(id:string|null) {
+  highlight(filenameAndId:string|null) {
+	this._highlight(filenameAndId, true);
+  }
+  
+  //highlight a marked block. If request is true, dispatch a fragment request if the block is not found.
+  private _highlight(filenameAndId:string|null, request:boolean) {
+    this.__highlightedBlock=filenameAndId;
     const div = this.querySelector('.highlight') as HTMLElement;
     
     div.style.removeProperty('top');
     div.style.removeProperty('height');
-    if (id!==null) {
+    if (filenameAndId!==null) {
+		
+		var ss = filenameAndId!.split('#',2);
+		var id = ss!.pop();
+		var filename = ss!.pop();
+		
         var begin = this.querySelector('.begin-'+id) as HTMLElement;
         var end = this.querySelector('.end-'+id) as HTMLElement;
-        if (begin && end && begin.offsetTop<=end.offsetTop) {
+        if (!begin || !end) {
+			if (request) {
+			  this.dispatchEvent(new CustomEvent('fragment-request', {bubbles: true, detail: {filename}}));
+			}			
+		} else if (begin.offsetTop<=end.offsetTop) {
             var top = begin.offsetTop;
             var height = end.offsetTop+end.offsetHeight-top;
             div.style.top= `calc( ${top}px + 0.75em)`;
diff --git a/src/test/java/com/flowingcode/vaadin/addons/demo/AdditionalSources.java b/src/test/java/com/flowingcode/vaadin/addons/demo/AdditionalSources.java
new file mode 100644
index 0000000..bf52132
--- /dev/null
+++ b/src/test/java/com/flowingcode/vaadin/addons/demo/AdditionalSources.java
@@ -0,0 +1,7 @@
+package com.flowingcode.vaadin.addons.demo;
+
+public class AdditionalSources {
+  // begin-block fragment
+  // this class has more sources
+  // end-block fragment
+}
diff --git a/src/test/java/com/flowingcode/vaadin/addons/demo/MultiSourceDemo.java b/src/test/java/com/flowingcode/vaadin/addons/demo/MultiSourceDemo.java
index c059d54..e7ceba9 100644
--- a/src/test/java/com/flowingcode/vaadin/addons/demo/MultiSourceDemo.java
+++ b/src/test/java/com/flowingcode/vaadin/addons/demo/MultiSourceDemo.java
@@ -18,26 +18,34 @@
  */
 package com.flowingcode.vaadin.addons.demo;
 
+import com.vaadin.flow.component.button.Button;
 import com.vaadin.flow.component.dependency.StyleSheet;
 import com.vaadin.flow.component.html.Div;
-import com.vaadin.flow.component.html.Span;
 import com.vaadin.flow.router.PageTitle;
 import com.vaadin.flow.router.Route;
 
 @Route(value = "demo/multisource", layout = Demo.class)
 @PageTitle("Demo with multiple sources")
 // show-source @DemoSource
+// show-source @DemoSource(clazz = AdditionalSources.class)
 // show-source @DemoSource("/src/test/resources/META-INF/resources/frontend/multi-source-demo.css")
-// show-source @DemoSource(clazz = Demo.class)
 @DemoSource
+@DemoSource(clazz = AdditionalSources.class)
 @DemoSource("/src/test/resources/META-INF/resources/frontend/multi-source-demo.css")
-@DemoSource(clazz = Demo.class)
 @StyleSheet("./multi-source-demo.css")
 public class MultiSourceDemo extends Div {
   public MultiSourceDemo() {
-    Span span = new Span("This is the main source");
-    span.addClassName("custom-style");
-    add(span);
+
+    // begin-block main
+    Div div = new Div("This is the main source");
+    div.addClassName("custom-style");
+    SourceCodeViewer.highlightOnHover(div, "main");
+    add(div);
+    // end-block
+
+    Button button1 = new Button("Highlight code in AdditionalSources");
+    SourceCodeViewer.highlightOnClick(button1, "AdditionalSources.java#fragment");
+    add(button1);
   }
 
 }