The first entry has to be called 'default'.

functions/identity.php

@@ -29,15 +29,16 @@ function get_identities() {
     $num_ids = getPref($data_dir,$username,'identities');
     $identities = array();
     /* We always have this one, even if the user doesn't use multiple identities */
-    $identities[] = array('full_name' => getPref($data_dir,$username,'full_name'),
+    $identities['default'] = array('full_name' => getPref($data_dir,$username,'full_name'),
         'email_address' => getPref($data_dir,$username,'email_address'),
         'reply_to' => getPref($data_dir,$username,'reply_to'),
         'signature' => getSig($data_dir,$username,'g'),
         'index' => 0 );
 
     /* If there are any others, add them to the array */
-    if (!empty($num_ids) && $num_ids > 1) {                                                                 for ($i=1;$i<$num_ids;$i++) {
-            $identities[] = array('full_name' => getPref($data_dir,$username,'full_name' . $i),
+    if (!empty($num_ids) && $num_ids > 1) {
+        for ($i=1;$i<$num_ids;$i++) {
+            $identities[$i] = array('full_name' => getPref($data_dir,$username,'full_name' . $i),
             'email_address' => getPref($data_dir,$username,'email_address' . $i),
             'reply_to' => getPref($data_dir,$username,'reply_to' . $i),
             'signature' => getSig($data_dir,$username,$i),