i tried the patch and the block is now working great when i disable 
the broken LIST-STATUS capability

yes i saw that it it cached, but the cache is capability cache is 
filled when logging in, because the server greets with the capabilitys 
and these are not filtered. i logged out and logged in (this was and 
is my testcase) and there no filtering is done. and if i see it 
correctly if cache is filled when calling capability() the cache is 
returned, regardless how it was filled, and it is filled in onother 
place too, when yuo log in and server sends the capabilitys

Yes, this was the issue.

Changes have been made in Git for this ticket:

Filter CAPABILITY return if sent in response code (Bug #9976)

  2 files changed, 14 insertions(+), 11 deletions(-)
http://git.horde.org/horde-git/-/commit/b01d678e4c796ffc10dfbd0cd4a85dc895aac72c

capability() is only called once per session - the capability list of 
the server is cached.  So this is working exactly as expected.

when the initial login to a server is done and the response send the 
capability list (net extra requested by capability command) the 
filtering of the capability_ignore is not done the are set as the 
capabilitys.

$servers['advanced'] = array(
     'disabled' => false,
     'name' => 'Advanced IMAP Server',
     'hostspec' => 'localhost',
     'hordeauth' => 'full',
     'protocol' => 'imap',
     'port' => 143,
     'secure' => false,
     'maildomain' => 'xxx',
     'smtphost' => 'xxx',
     'smtpport' => 25,
     'capability_ignore' => array("LIST-STATUS"),
     'debug' => "/tmp/imaplog",
     'debug_raw' => true,
     'quota' => array(
         'driver' => 'imap',
         'params' => array(
             'hide_when_unlimited' => true,
             'unit' => 'MB'
         )
     ),
     'acl' => true,
     'cache' => false,
);

i added in the function capability() a die() right before the return 
statement in Client/Base.php and execution dies only when calling imp 
directly and not when viewing the block or the sidemenu. this is also 
the only one place where i found that capability_ignore param is 
checked and used. also i added a var_dump right before the return 
instead the die(), now when i open imp i got some more lines that say 
that LIST-STATUS is 1, i expected that it is 0 or no longer in the 
capability array. i can also see still the LIST-STATUS calls in the 
imaplog when i turn on debugging for my server in backends.local.php.

I do not understand what you are saying.  It does not matter whether 
you are viewing via a block or within imp itself - IMP is using the 
same internal object (with the same config) to access the IMAP server.

i have no chance to upgrade dovecot so i tried to disable the 
LIST-STATUS in my backends.local.php but for the block the 
ignore_capability setting is not used only when i open imp i can see 
in Socket.php that it is not used any more

It appears that your version of Dovecot is broken and is not properly 
handling RFC 5819 LIST-STATUS requests.  I can verify version 2.0.12 
works correctly.

Since this is not a critical issue and doesn't break anything, I am 
not going to implement a workaround.

can you please have a look at the imaplog file, first part is the 
block loading, second part is the navigation tree loading

for me it seems there is something bad with the LIST command and the 
subfoldernames

This doesn't help at all.  Nobody else can reproduce, and it doesn't 
look like it has anything to do with subfolders since I have all sorts 
of subfolders that are polled for mail and they show up fine.

You will have to debug yourself and figure out why those mailboxes are 
not being displayed in your system.  The call that generates the 
polled list is located on line 69 of imp/lib/Block/Summary.php:
         $poll = $injector->getInstance('IMP_Imap_Tree')->getPollList(true);

attached another screenshot whith the menu / the block and the folder 
configuration, i hope this bring some light in the dark

configuration screenshot

i have not set up these option in the block, i attach my portal layout 
and a screenshot from block configuration.

My guess is that you have the show_unread option set.

the problem is only in the imp block "Folder summary", folder list is 
showing all right, menu is also all doing it right only the block 
doesn't show the folders in subfolder of INBOX. all is the traditional 
view

Can't reproduce. Are those folders polled in the sidebar menu and in 
the folder navigator of the traditional view? How about the dynamic 
view?

the check for new messages only work in INBOX and subfolders under 
INBOX, if i set the check up for a folder in a subfolder under INBOX 
it is not shown

i have set up a block with folder summary, but only te inbox is shown, 
but i have set up the check for new messages option for many more 
folders, the option to only show the folders with new messages makes 
no differences