diff -r d0eb4fb4bc55 netx/net/sourceforge/swing/SwingUtils.java
--- a/netx/net/sourceforge/swing/SwingUtils.java	Thu Oct 18 13:09:29 2018 +0200
+++ b/netx/net/sourceforge/swing/SwingUtils.java	Thu Oct 18 21:32:37 2018 +0200
@@ -40,6 +40,17 @@
 import java.awt.EventQueue;
 import java.awt.Window;
 import java.lang.reflect.InvocationTargetException;
+/* <EDT_BRIDGE> */
+import java.util.concurrent.Callable;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Future;
+import java.util.concurrent.LinkedBlockingQueue;
+import java.util.concurrent.ThreadFactory;
+import java.util.concurrent.ThreadPoolExecutor;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicInteger;
+/* </EDT_BRIDGE> */
 import javax.swing.JWindow;
 import javax.swing.RepaintManager;
 import javax.swing.SwingUtilities;
@@ -49,6 +60,7 @@
 /**
  * Swing / AWT utility class
  */
+
 public final class SwingUtils {
 
     private static final boolean DEBUG_EDT = System.getProperty("icedtea-web.edt.debug", "false").equalsIgnoreCase("true");
@@ -67,6 +79,51 @@
     /* shared Window owner */
     private static Window window = null;
 
+/* <EDT_BRIDGE> */
+    private static final boolean TRACE_BRIDGE = false;
+    
+    private static final boolean ENABLE_EDT_BRIDGE;
+
+    /** single thread pool with max 1 live daemon thread */
+    private static final ExecutorService EDT_DAEMON_THREAD_POOL;
+
+    static {
+        ENABLE_EDT_BRIDGE = System.getProperty("icedtea-web.edt.bridge", "false").equalsIgnoreCase("true");
+        if (ENABLE_EDT_BRIDGE) {
+            trace("Enable EDT Bridge.");
+
+            EDT_DAEMON_THREAD_POOL = new ThreadPoolExecutor(0, 1,
+                    60L, TimeUnit.SECONDS,
+                    new LinkedBlockingQueue<Runnable>(),
+                    new MainAppContextDaemonThreadFactory()
+            );
+        } else {
+            EDT_DAEMON_THREAD_POOL = null;
+        }
+    }
+
+    private static final class MainAppContextDaemonThreadFactory implements ThreadFactory {
+
+        private final AtomicInteger threadNumber = new AtomicInteger(1);
+        private final String namePrefix = "itw-edt-thread-";
+
+        @Override
+        public Thread newThread(Runnable r) {
+            final Thread t = new Thread(MAIN_GROUP, r,
+                    namePrefix + threadNumber.getAndIncrement()
+            );
+            if (!t.isDaemon()) {
+                t.setDaemon(true);
+            }
+            if (t.getPriority() != Thread.NORM_PRIORITY) {
+                t.setPriority(Thread.NORM_PRIORITY);
+            }
+            return t;
+        }
+    }
+
+/* </EDT_BRIDGE> */
+
     private SwingUtils() {
         // forbidden
     }
@@ -134,6 +191,31 @@
                 traceWithStack("invokeLater() from EDT: MAY be fixed (useless) ?");
             }
         }
+/* <EDT_BRIDGE> */
+        else if (ENABLE_EDT_BRIDGE) {
+            // AppContext bridge
+            final ClassLoader doRunCL = doRun.getClass().getClassLoader();
+
+            if (TRACE_BRIDGE) {
+                trace("invokeLater(doRun): "
+                        + doRun.getClass().getName() + " @ "
+                        + ((doRunCL == null) ? "BootClassLoader" : doRunCL));
+            }
+
+            // Ensure bridge is only used by Boot class loader:
+            if (doRunCL == null) {
+                EDT_DAEMON_THREAD_POOL.submit(new Runnable() {
+                    @Override
+                    public void run() {
+                        SwingUtilities.invokeLater(doRun);
+                    }
+                });
+                return;
+            } else {
+                traceWithStack("SwingUtils.invokeLater() called from external class loader: " + doRunCL);
+            }
+        }
+/* </EDT_BRIDGE> */
         EventQueue.invokeLater(doRun);
     }
 
@@ -150,6 +232,44 @@
     }
 
     public static void invokeAndWait(final Runnable doRun) {
+/* <EDT_BRIDGE> */
+        if (!isMainThreadGroup() && ENABLE_EDT_BRIDGE) {
+            // AppContext bridge
+            final ClassLoader doRunCL = doRun.getClass().getClassLoader();
+
+            if (TRACE_BRIDGE) {
+                trace("invokeAndWait(doRun): "
+                        + doRun.getClass().getName() + " @ "
+                        + ((doRunCL == null) ? "BootClassLoader" : doRunCL));
+            }
+
+            // Ensure bridge is only used by Boot class loader:
+            if (doRunCL == null) {
+                final Future<?> future = EDT_DAEMON_THREAD_POOL.submit(new Callable<Void>() {
+                    @Override
+                    public Void call() throws Exception {
+                        callOnAppContext(doRun);
+                        return null;
+                    }
+                });
+                try {
+                    // Wait on Future:
+                    future.get();
+                } catch (InterruptedException ie) {
+                    OutputController.getLogger().log(OutputController.Level.ERROR_ALL, ie);
+                } catch (ExecutionException ee) {
+                    if (ee.getCause() != null) {
+                        OutputController.getLogger().log(OutputController.Level.ERROR_ALL, ee.getCause());
+                    } else {
+                        OutputController.getLogger().log(OutputController.Level.ERROR_ALL, ee);
+                    }
+                }
+                return;
+            } else {
+                traceWithStack("SwingUtils.invokeAndWait() called from external class loader: " + doRunCL);
+            }
+        }
+/* </EDT_BRIDGE> */
         if (isEventDispatchThread()) {
             if (TRACE_INVOKE_EDT) {
                 traceWithStack("invokeAndWait() from EDT: to be fixed (illegal) ?");