Index: /trunk/src/org/openstreetmap/josm/gui/tagging/ac/AutoCompletingComboBox.java
===================================================================
--- /trunk/src/org/openstreetmap/josm/gui/tagging/ac/AutoCompletingComboBox.java	(revision 5482)
+++ /trunk/src/org/openstreetmap/josm/gui/tagging/ac/AutoCompletingComboBox.java	(revision 5483)
@@ -222,5 +222,5 @@
     public void setPossibleItems(Collection<String> elems) {
         DefaultComboBoxModel model = (DefaultComboBoxModel)this.getModel();
-        Object oldValue = getSelectedItem();
+        Object oldValue = this.getEditor().getItem(); // Do not use getSelectedItem(); (fix #8013)
         model.removeAllElements();
         for (String elem : elems) {
@@ -230,5 +230,5 @@
         // AutoCompletingComboBoxDocument#insertString
         autocompleteEnabled = false;
-        setSelectedItem(oldValue);
+        this.getEditor().setItem(oldValue); // Do not use setSelectedItem(oldValue); (fix #8013)
         autocompleteEnabled = true;
     }
@@ -240,4 +240,5 @@
         DefaultComboBoxModel model = (DefaultComboBoxModel)this.getModel();
         Object oldValue = getSelectedItem();
+        Object editorOldValue = this.getEditor().getItem();
         model.removeAllElements();
         for (AutoCompletionListItem elem : elems) {
@@ -245,4 +246,5 @@
         }
         setSelectedItem(oldValue);
+        this.getEditor().setItem(editorOldValue);
     }