Index: trunk/src/org/openstreetmap/josm/gui/tagging/ac/MaxLengthDocumentFilter.java
===================================================================
--- trunk/src/org/openstreetmap/josm/gui/tagging/ac/MaxLengthDocumentFilter.java	(revision 18234)
+++ trunk/src/org/openstreetmap/josm/gui/tagging/ac/MaxLengthDocumentFilter.java	(revision 18236)
@@ -1,4 +1,6 @@
 // License: GPL. For details, see LICENSE file.
 package org.openstreetmap.josm.gui.tagging.ac;
+
+import static org.openstreetmap.josm.tools.I18n.tr;
 
 import javax.swing.text.AttributeSet;
@@ -14,4 +16,5 @@
     /** the document will not accept text longer than this. -1 to disable */
     private int maxLength = -1;
+    private static final String DIFFERENT = tr("<different>");
 
     /**
@@ -42,5 +45,5 @@
     private boolean mustInsertOrReplace(FilterBypass fb, int length, String string, AttributeSet attr) {
         int newLen = fb.getDocument().getLength() - length + ((string == null) ? 0 : string.length());
-        return (maxLength == -1 || newLen <= maxLength ||
+        return (maxLength == -1 || newLen <= maxLength || DIFFERENT.equals(string) ||
                 // allow longer text while composing characters or it will be hard to compose
                 // the last characters before the limit