For heavy forum users (especially moderators/admins;), here is a little script you can add to your Mass Move link (or as a separate link) to create a checkbox and set/unset all checkboxes with one click. It can be useful not only for mass moving but also mass deleting of posts. All you have to do is to open bb_plugins.php, find: $massMoveLink and extend it to the code in bold:
$massMoveLink="{$l_sepr} <a href=\"JavaScript:massMove();\">{$l_moveMass}</a> <script>function toggle(source){checkboxes = document.getElementsByName('deleteAll[]');for(var i=0, n=checkboxes.length;i<n;i++) {checkboxes[i].checked = source.checked;}}</script><label><input type=\"checkbox\" onClick=\"toggle(this);\" />Toggle All</label>";
