I might consider this as an advanced preference if a patch was 
provided.  But only in IMP 5 - this won't be backported to IMP 4.
No.  Trash is enabled.  It is expensive to search a mailbox to 
determine if there are messages marked as deleted just to activate a 
UI element.  This should not be overhead for every mailbox viewed when 
using the trash.
Sure there is.  Just select the message you want and click on delete.   
Adding an expunge button requires just as much effort, while 
cluttering the UI with an option a user has explicitly said they don't 
want to deal with (Trash implies no expunging is needed).

OK, I see you point..

How about one of these options..

1) Provide an option that allows horde to "use the trash", "hide 
deleted messages", and NOT auto expunge?
* which can lead to the issue of users never expunging, but that 
happens already w/ trash disabled and delhide enabled

When trash is enabled, provide UI elements to either
2)  allow user to manually hide deleted (default always to show) and a 
button to expunge deleted messages
3) OR just put a button back in the UI to expunge the deleted messages.
This last one is the REAL issue I have I guess.   When I have trash 
enabled there is no obvious way to expunge/purge those "marked 
deleted" messages from my mailbox via horde.

No.  It is a *terrible* idea to assume that deleted flags that exist 
in a mailbox mean that they should be moved to the trash (or, even 
worse, expunged automatically and permanently).  IMP can't guess what 
other MUAs intend when they mark messages as deleted.  Thus, the only 
safe and sane option is to show these messages as flagged deleted, but 
requiring a user to take a proactive action to indicate that yes, 
indeed, he really does want those messages permanently deleted from 
the mailbox.

I too am having this issue..  The issue being using several "other" 
applications outside of horde do not follow the "horde" philosophy of 
immediately purging the folder when moving mail into the trash.  Thus 
when telling horde to use the "trash" I see a cluttering of "deleted" 
messages in the horde inbox.

Mail client I use (outside of horde) on a regular basis..

Thunderbird 3.1
Apple Mail (snow leopard version)
iPad mail client (4.3.1)
iPhone mail client (3.1.3)

So for compatibility with other client, having the ability to USE the 
trash AND hide deleted is a BIG plus. (Note that I am using Horde4/Imp5)

I remain unvoncinced. Delete-but-not-expunged messages can be left by 
other applications than IMP. The user may wish to hide those. I see no 
point in removing that choice from the user. What is *achieved* by that?



I'm applying this patch to the version distributed by Debian:



--- orig/lib/Mailbox.php

+++ mod/lib/Mailbox.php

@@ -171,7 +171,6 @@

              $this->_delhide = !$GLOBALS['imp_search']->isVTrashFolder();

          } else {

              $this->_delhide = ($GLOBALS['prefs']->getValue('delhide') &&

-                               !$GLOBALS['prefs']->getValue('use_trash') &&

                                 ($GLOBALS['imp_search']->isSearchMbox() ||

                                 
($GLOBALS['prefs']->getValue('sortby') != SORTTHREAD)));

          }

Hi,



I reported this bug on the debian bugtracker but in fact, I saw 
deleted messages with use_trash enabled because I opened horde/imp 
while my thunderbird was still opened, so my mailbox was not yet 
expunged by thunderbird.



So this problem would happen on very seldom cases (thunderbird crashes 
and i connect after on horde), but I still think it would be better to 
enable delhide when use_trash is enabled so that it never happens.



What is the problem with enabling delhide with use_trash ?

No, this doesn't happen here. The mailbox is expunged after the 
message has been moved to trash.

But if one uses the trash folder, when a deleted message gets moved, 
it still appears deleted in the original folder, until one expunges 
it. Surely you want to avoid that.

No, either you use a trash folder, or the delete flag. Never both. If 
you use the trash folder, delete messages are move there, so it 
doesn't make sense to hide deleted messages - there are none.

When the use_trash preference is enabled, the value of the delhide 
preference is ignored and effectively forced off. Didn't you mean on 
the contrary to force it *on* when use_trash is on?



That is, replace in lib/Mailbox.php:



             $this->_delhide = ($GLOBALS['prefs']->getValue('delhide') &&

                                !$GLOBALS['prefs']->getValue('use_trash') &&

                                ($GLOBALS['imp_search']->isSearchMbox() ||

                                ($GLOBALS['prefs']->getValue('sortby') 
!= SORTTHREAD)));



by



             $this->_delhide = (($GLOBALS['prefs']->getValue('delhide') ||

                                !$GLOBALS['prefs']->getValue('use_trash')) &&

                                ($GLOBALS['imp_search']->isSearchMbox() ||

                                ($GLOBALS['prefs']->getValue('sortby') 
!= SORTTHREAD)));