diff -Naur squirrelmail-1.4.15/functions/forms.php squirrelmail-1.4.15.oden/functions/forms.php
--- squirrelmail-1.4.15/functions/forms.php	2008-04-30 01:27:48.000000000 +0200
+++ squirrelmail-1.4.15.oden/functions/forms.php	2008-06-26 19:42:47.000000000 +0200
@@ -41,6 +41,7 @@
  */
 function addCheckBox($name, $checked = false, $value = null, $extra_attributes='') {
     return addInputField('checkbox', $name, $value,
+        concat_hook_function('checkbox_extra_params', $name) . ' ' .
         ($checked ? ' checked="checked"' : '') . $extra_attributes);
 }
 
diff -Naur squirrelmail-1.4.15/functions/mailbox_display.php squirrelmail-1.4.15.oden/functions/mailbox_display.php
--- squirrelmail-1.4.15/functions/mailbox_display.php	2008-02-10 17:49:47.000000000 +0100
+++ squirrelmail-1.4.15.oden/functions/mailbox_display.php	2008-06-26 19:42:47.000000000 +0200
@@ -208,7 +208,7 @@
             case 1: /* checkbox */
                 echo html_tag( 'td',
                                "<input type=\"checkbox\" name=\"msg[$t]\" id=\"msg".$msg['ID'].
-                                   "\" value=\"".$msg['ID']."\"$checked>",
+                                   "\" value=\"".$msg['ID']."\"$checked " . concat_hook_function('checkbox_extra_params', "msg[$t]") . ">",
                                'center',
                                $hlt_color );
                 break;
@@ -973,6 +973,8 @@
         $result .= "</a>\n";
     }
 
+    $result .= concat_hook_function('mailbox_selectall_after');
+
     /* Return our final result. */
     return ($result);
 }