when falling back to the default theme, set $chosen_theme to the path

of default to make functions that depend on $chosen_theme work
correctly (most notably the select list under display preferences which
would have Alien Glow selected when user has no theme set). Thanks Tim Craig
for the bugreport.

ChangeLog

@@ -60,6 +60,8 @@ Version 1.5.0 -- CVS
   - Fix when forwarding messages as attachment from message list, the displayed subject
     was wrong (appearing to the user that the wrong messages were attached).
     Closes #772371.
+  - Fix that when user has no theme preference set, Alien Glow would be selected under
+    display preferences in stead of Default.
 
 **************************************
 *** SquirrelMail Stable Series 1.4 ***

include/load_prefs.php

@@ -46,6 +46,7 @@ if (isset($chosen_theme) && $found_theme && (file_exists($chosen_theme))) {
 } else {
     if (isset($theme) && isset($theme[$theme_default]) && file_exists($theme[$theme_default]['PATH'])) {
         @include_once($theme[$theme_default]['PATH']);
+        $chosen_theme = $theme[$theme_default]['PATH'];
     } else {
         /**
          * This theme as a failsafe if no themes were found. It makes