Index: /trunk/src/org/openstreetmap/josm/gui/widgets/ComboBoxHistory.java
===================================================================
--- /trunk/src/org/openstreetmap/josm/gui/widgets/ComboBoxHistory.java	(revision 2218)
+++ /trunk/src/org/openstreetmap/josm/gui/widgets/ComboBoxHistory.java	(revision 2219)
@@ -39,4 +39,6 @@
     private int maxSize = 10;
 
+    private List<HistoryChangedListener> listeners = new ArrayList<HistoryChangedListener>();
+
     public ComboBoxHistory(int size) {
         maxSize = size;
@@ -69,4 +71,6 @@
         // set selected item to the one just added
         setSelectedItem(o);
+
+        fireHistoryChanged();
     }
 
@@ -110,3 +114,17 @@
         return list;
     }
+
+    public void addHistoryChangedListener(HistoryChangedListener l) {
+        listeners.add(l);
+    }
+
+    public void removeHistoryChangedListener(HistoryChangedListener l) {
+        listeners.remove(l);
+    }
+
+    private void fireHistoryChanged() {
+        for (HistoryChangedListener l : listeners) {
+            l.historyChanged(asList());
+        }
+    }
 }
Index: /trunk/src/org/openstreetmap/josm/gui/widgets/HistoryChangedListener.java
===================================================================
--- /trunk/src/org/openstreetmap/josm/gui/widgets/HistoryChangedListener.java	(revision 2219)
+++ /trunk/src/org/openstreetmap/josm/gui/widgets/HistoryChangedListener.java	(revision 2219)
@@ -0,0 +1,34 @@
+/* Copyright (c) 2008, Henrik Niehaus
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ * 3. Neither the name of the project nor the names of its
+ *    contributors may be used to endorse or promote products derived from this
+ *    software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+package org.openstreetmap.josm.gui.widgets;
+
+import java.util.List;
+
+public interface HistoryChangedListener {
+    public void historyChanged(List<String> history);
+}