Added javascript portion of the drop functionality. At this point you can drag selected images and drop them on the micro thumb grid in a different position or onto a branch in the gallery tree. No ajax call is made, it just writes the generated url and post data to the console, so it only works in ff right now.

modules/organize/views/organize_dialog.html.php

@@ -1,4 +1,7 @@
 <?php defined("SYSPATH") or die("No direct script access.") ?>
+<script type="text/javascript">
+  var drop_url = "<?= url::site("organize/drop/__PARENT_ID__/__POSITION__/__TARGET_ID__?csrf=$csrf") ?>";
+</script>
 <div id="gOrganize" class="gDialogPanel">
   <h1 style="display:none"><?= t("Organize %name", array("name" => p::purify($title))) ?></h1>
   <div id="bd">