Fixed in HEAD and 4.0.3.

Create a Virtual Folder, open it using the block in the left frame 
then if you click in the mailbox view on the edit link and save the 
folder again, you get a duplicate folder which is corrupt (unserialize 
error)

As I see it IMP tries to delete the folder without the 
IMP_VFOLDER_PREFIX appended.

This problem can be avoided by using the folder view in IMP and 
clicking on the edit link next to the folder.



I tried to solve this by adding this function to lib/VFolder.php:

     /**

      * Add the IMP identifying label (if needed) to a virtual folder ID.

      *

      * @access public

      *

      * @param string $id  The virtual folder ID.

      *

      * @return string  The virtual folder name, with the IMP specific 
identifying

      *                 information added.

      */

     function getIMPLabel($id)

     {

         $id=IMP_VFolder::_stripIMPLabel($id);

         return IMP_VFOLDER_PREFIX . $id;

     }



And modifying search.php on line 301:

$imptree->delete($edit_vfolder_id);

to:

$imptree->delete(IMP_VFolder::getIMPLabel($edit_vfolder_id));



Another approach would be to change editVFolderURL in lib/VFolder.php 
to always add the IMP_VFOLDER_PREFIX to the folder_id parameter ( You 
need the extra function getIMPlabel too).

File lib/VFolder.php line 278:

         return 
Util::addParameter(Horde::applicationUrl('search.php'), 
array('edit_vfolder' => 1, 'vfolder' => $id));

to:

         return 
Util::addParameter(Horde::applicationUrl('search.php'), 
array('edit_vfolder' => 1, 'vfolder' => 
IMP_VFolder::getIMPLabel($edit_vfolder_id));



I personally prefer the first method, although both patches can be 
implemented together with no problems and this would create more 
unified links.