Index: trunk/src/org/openstreetmap/josm/gui/MainApplication.java
===================================================================
--- trunk/src/org/openstreetmap/josm/gui/MainApplication.java	(revision 16049)
+++ trunk/src/org/openstreetmap/josm/gui/MainApplication.java	(revision 16050)
@@ -63,5 +63,4 @@
 import javax.swing.UnsupportedLookAndFeelException;
 
-import org.jdesktop.swinghelper.debug.CheckThreadViolationRepaintManager;
 import org.openstreetmap.josm.actions.DeleteAction;
 import org.openstreetmap.josm.actions.JosmAction;
@@ -121,4 +120,5 @@
 import org.openstreetmap.josm.gui.preferences.server.ProxyPreference;
 import org.openstreetmap.josm.gui.progress.swing.ProgressMonitorExecutor;
+import org.openstreetmap.josm.gui.util.CheckThreadViolationRepaintManager;
 import org.openstreetmap.josm.gui.util.GuiHelper;
 import org.openstreetmap.josm.gui.util.RedirectInputMap;
Index: trunk/src/org/openstreetmap/josm/gui/util/CheckThreadViolationRepaintManager.java
===================================================================
--- trunk/src/org/openstreetmap/josm/gui/util/CheckThreadViolationRepaintManager.java	(revision 16050)
+++ trunk/src/org/openstreetmap/josm/gui/util/CheckThreadViolationRepaintManager.java	(revision 16050)
@@ -0,0 +1,107 @@
+/*
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+package org.openstreetmap.josm.gui.util;
+
+import java.lang.ref.WeakReference;
+
+import javax.swing.JComponent;
+import javax.swing.RepaintManager;
+import javax.swing.SwingUtilities;
+
+import org.openstreetmap.josm.tools.Logging;
+
+/**
+ * <p>This class is used to detect Event Dispatch Thread rule violations<br>
+ * See <a href="http://java.sun.com/docs/books/tutorial/uiswing/misc/threads.html">How to Use Threads</a>
+ * for more info</p>
+ * <p/>
+ * <p>This is a modification of original idea of Scott Delap<br>
+ * Initial version of ThreadCheckingRepaintManager can be found here<br>
+ * <a href="http://www.clientjava.com/blog/2004/08/20/1093059428000.html">Easily Find Swing Threading Mistakes</a>
+ * </p>
+ *
+ * @author Scott Delap
+ * @author Alexander Potochkin
+ *
+ * https://swinghelper.dev.java.net/
+ */
+public class CheckThreadViolationRepaintManager extends RepaintManager {
+    private WeakReference<JComponent> lastComponent;
+
+    @Override
+    public synchronized void addInvalidComponent(JComponent component) {
+        checkThreadViolations(component);
+        super.addInvalidComponent(component);
+    }
+
+    @Override
+    public void addDirtyRegion(JComponent component, int x, int y, int w, int h) {
+        checkThreadViolations(component);
+        super.addDirtyRegion(component, x, y, w, h);
+    }
+
+    private void checkThreadViolations(JComponent c) {
+        if (!SwingUtilities.isEventDispatchThread()) {
+            boolean repaint = false;
+            boolean fromSwing = false;
+            boolean imageUpdate = false;
+            StackTraceElement[] stackTrace = Thread.currentThread().getStackTrace();
+            for (StackTraceElement st : stackTrace) {
+                if (repaint && st.getClassName().startsWith("javax.swing.") &&
+                    // for details see https://swinghelper.dev.java.net/issues/show_bug.cgi?id=1
+                    !st.getClassName().startsWith("javax.swing.SwingWorker")) {
+                    fromSwing = true;
+                }
+                if (repaint && "imageUpdate".equals(st.getMethodName())) {
+                    imageUpdate = true;
+                }
+                if ("repaint".equals(st.getMethodName())) {
+                    repaint = true;
+                    fromSwing = false;
+                }
+                if ("read".equals(st.getMethodName()) && "javax.swing.JEditorPane".equals(st.getClassName())) {
+                    // Swing reads html from a background thread
+                    return;
+                }
+            }
+            if (imageUpdate) {
+                //assuming it is java.awt.image.ImageObserver.imageUpdate(...)
+                //image was asynchronously updated, that's ok
+                return;
+            }
+            if (repaint && !fromSwing) {
+                //no problems here, since repaint() is thread safe
+                return;
+            }
+            //ignore the last processed component
+            if (lastComponent != null && c == lastComponent.get()) {
+                return;
+            }
+            lastComponent = new WeakReference<>(c);
+            violationFound(c, stackTrace);
+        }
+    }
+
+    protected static void violationFound(JComponent c, StackTraceElement[] stackTrace) {
+        Logging.error("");
+        Logging.error("EDT violation detected");
+        Logging.error(c.toString());
+        for (StackTraceElement st : stackTrace) {
+            Logging.error("\tat " + st);
+        }
+    }
+}