Index: /src/org/openstreetmap/josm/gui/dialogs/EditableComboBox.java
===================================================================
--- /src/org/openstreetmap/josm/gui/dialogs/EditableComboBox.java	(revision 253)
+++ /src/org/openstreetmap/josm/gui/dialogs/EditableComboBox.java	(revision 253)
@@ -0,0 +1,227 @@
+package org.openstreetmap.josm.gui.dialogs;
+import java.awt.Component;
+import java.awt.event.ActionListener;
+import java.util.ArrayList;
+import java.util.Iterator;
+import java.util.List;
+
+import javax.swing.AbstractListModel;
+import javax.swing.ComboBoxEditor;
+import javax.swing.JComboBox;
+import javax.swing.JTextField;
+import javax.swing.MutableComboBoxModel;
+import javax.swing.event.DocumentEvent;
+import javax.swing.event.DocumentListener;
+
+/**
+ * {@link JComboBox} that filters values from its model according to the input given up to now.
+ * 
+ * Code taken from http://forum.java.sun.com/thread.jspa?threadID=712032&messageID=4123364
+ * Modified by cdaller (Christof Dallermassl)
+ * 
+ * @author Senthilkumar, cdaller
+ *
+ */
+public class EditableComboBox extends JComboBox {
+
+	/**
+	 * Initialize without data.
+	 */
+	public EditableComboBox() {
+		this(new ArrayList());
+	}
+
+	/**
+	 * Set the given list as values into the model.
+	 * @param items the items.
+	 */
+	public EditableComboBox(List items) {
+		setModel(new FilterableComboBoxModel(items));
+		setEditor(new MyEditor());
+		setEditable(true);
+	}
+
+	/**
+	 * The combo model that allows to filter values.
+	 */
+	public static class FilterableComboBoxModel extends AbstractListModel
+	implements MutableComboBoxModel {
+
+		private List items;
+		private Filter filter;
+		private List filteredItems;
+		private Object selectedItem;
+
+		public FilterableComboBoxModel(List items) {    
+			this.items = new ArrayList(items);
+			filteredItems = new ArrayList(items.size());
+			updateFilteredItems();
+		}
+
+		public void addElement(Object obj) {      
+			items.add(obj);
+			updateFilteredItems();
+		}
+
+		public void removeElement(Object obj) {     
+			items.remove(obj);
+			updateFilteredItems();
+		}
+
+		public void removeElementAt(int index) {      	
+			items.remove(index);
+			updateFilteredItems();
+		}
+
+		public void insertElementAt(Object obj, int index) {}
+
+		public void setFilter(Filter filter) {         
+			this.filter = filter;
+			updateFilteredItems();
+		}
+
+		protected void updateFilteredItems() {       
+			fireIntervalRemoved(this, 0, filteredItems.size());
+			filteredItems.clear();
+
+			if (filter == null)
+				filteredItems.addAll(items);
+			else {
+				for (Iterator iterator = items.iterator(); iterator.hasNext();) {
+
+					Object item = iterator.next();
+
+					if (filter.accept(item))
+						filteredItems.add(item);
+				}
+			}
+			fireIntervalAdded(this, 0, filteredItems.size());
+		}
+
+		public int getSize() {
+			return filteredItems.size();
+		}
+
+		public Object getElementAt(int index) {
+			return filteredItems.get(index);
+		}
+
+		public Object getSelectedItem() {
+			return selectedItem;
+		}
+
+		public void setSelectedItem(Object val) {      
+			if ((selectedItem == null) && (val == null))
+				return;
+
+			if ((selectedItem != null) && selectedItem.equals(val))
+				return;
+
+			if ((val != null) && val.equals(selectedItem))
+				return;
+
+			selectedItem = val;
+			fireContentsChanged(this, -1, -1);
+		}
+	}
+
+	/**
+	 * Filter interface
+	 */
+	public static interface Filter {
+		/**
+		 * Returns <code>true</code> if the object is accepted, <code>false</code> otherwise.
+		 * @param obj the object to filter.
+		 * @return <code>true</code> if the object is accepted, <code>false</code> otherwise.
+		 */
+		public boolean accept(Object obj);
+	}
+
+	/**
+	 * Implementation of the filter that checks for trailing equality of strings.
+	 */
+	public static class StartsWithFilter implements Filter {
+
+		private String prefix;
+		public StartsWithFilter(String prefix) { this.prefix = prefix; }
+		public boolean accept(Object o) { return o.toString().startsWith(prefix); }
+	}
+
+	/**
+	 * Implementation of the filter that checks for trailing equality of strings.
+	 */
+	public static class StartsWithIgnoreCaseFilter implements Filter {
+
+		private String prefix;
+		public StartsWithIgnoreCaseFilter(String prefix) { this.prefix = prefix.toLowerCase(); }
+		public boolean accept(Object o) { return o.toString().toLowerCase().startsWith(prefix); }
+	}
+
+	/**
+	 * Editor for combobox that sets the filter according to the input given.
+	 */
+	public class MyEditor implements ComboBoxEditor, DocumentListener {
+
+		public JTextField text;
+		private volatile boolean filtering = false;
+		private volatile boolean setting = false;
+
+		public MyEditor() {
+
+			text = new JTextField(15);
+			text.getDocument().addDocumentListener(this);
+		}
+
+		public Component getEditorComponent() { return text; }
+
+		public void setItem(Object item) {
+
+			if(filtering)
+				return;
+
+			setting = true;
+			String newText = (item == null) ? "" : item.toString();
+			text.setText(newText);
+			setting = false;
+		}
+
+		public Object getItem() {
+			return text.getText();
+		}
+
+		public void selectAll() { text.selectAll(); }
+
+		public void addActionListener(ActionListener l) {
+			text.addActionListener(l);
+		}
+
+		public void removeActionListener(ActionListener l) {
+			text.removeActionListener(l);
+		}
+
+		public void insertUpdate(DocumentEvent e) { 
+			handleChange(); 
+		}
+		public void removeUpdate(DocumentEvent e) { 
+			handleChange(); 
+		}
+		public void changedUpdate(DocumentEvent e) { }
+
+		protected void handleChange() {
+			if (setting)
+				return;
+
+			filtering = true;
+
+			Filter filter = null;
+			if (text.getText().length() > 0)
+				filter = new StartsWithIgnoreCaseFilter(text.getText());
+
+			((FilterableComboBoxModel) getModel()).setFilter(filter);
+			// A bit nasty but it seems to get the popup validated properly
+			setPopupVisible(false);
+			setPopupVisible(true);
+			filtering = false;
+		}
+	}
+}
Index: /src/org/openstreetmap/josm/gui/dialogs/PropertiesDialog.java
===================================================================
--- /src/org/openstreetmap/josm/gui/dialogs/PropertiesDialog.java	(revision 252)
+++ /src/org/openstreetmap/josm/gui/dialogs/PropertiesDialog.java	(revision 253)
@@ -13,4 +13,5 @@
 import java.awt.event.ActionListener;
 import java.awt.event.KeyEvent;
+import java.awt.event.KeyListener;
 import java.awt.event.MouseAdapter;
 import java.awt.event.MouseEvent;
@@ -193,5 +194,5 @@
 		for (int i = 0; i < data.getRowCount(); ++i)
 			allData.remove(data.getValueAt(i, 0));
-		final JComboBox keys = new JComboBox(new Vector<String>(allData.keySet()));
+		final JComboBox keys = new EditableComboBox(new Vector<String>(allData.keySet()));
 		keys.setEditable(true);
 		p.add(keys, BorderLayout.CENTER);
@@ -200,5 +201,5 @@
 		p.add(p2, BorderLayout.SOUTH);
 		p2.add(new JLabel(tr("Please select a value")), BorderLayout.NORTH);
-		final JComboBox values = new JComboBox();
+		final JComboBox values = new EditableComboBox();
 		values.setEditable(true);
 		p2.add(values, BorderLayout.CENTER);
@@ -211,7 +212,8 @@
 					Vector<String> newValues = new Vector<String>(allData.get(key));
 					Object oldValue = values.getSelectedItem();
-					values.setModel(new DefaultComboBoxModel(newValues));
-					values.setSelectedItem(oldValue);
-					values.getEditor().selectAll();
+                          
+					values.setModel(new EditableComboBox.FilterableComboBoxModel(newValues));
+					// select the new proposed value
+					values.getEditor().selectAll();	
 				}
             }