changing to png solved the issues about not rotating the pics and also 
when deleting the picture

I'm pretty sure that what happened to you was due to an error in the 
way the gallery style properties were saved when using JPG images and 
a transparent gallery background color.

The property screen has been changed so it now disallows saving 
combinations of values that would be unsupported when using JPG images.

Please let me know if this solves the issue for you (in a newly 
created gallery).

Changes have been made in Git for this ticket:

Provide some verification and feedback if the style selection is not 
supported with the current image type.
Related to Bug: 10645

  2 files changed, 24 insertions(+), 4 deletions(-)
http://git.horde.org/horde-git/-/commit/cc96f9466681fea83395d42f5a384180b56594dc

Tracked this down to the fact that you are using JPG images.  Since 
JPG images cannot have a transparent background, choosing a background 
of 'none' causes Ansel to revert back to the "Plain" thumbnail type.

We need to provide better UI clues, filtering to reflect this.

when i create/edit i can select other thumbnail styles from dropdown 
but when i reopen the properties it shows everytime Basic Thumbnails, 
that's right. i my logs with log level DEBUG i only found some 
messages about missing permission for ansel:admin.

Ok, so to recap:

When you create/edit a gallery you are unable to select anything other 
than "Basic Thumbnails" for the Thumbnail style and that is causing 
the ansel_hashes table to not be populated. Is this correct?

I assume you have checked the horde/server logs for errors? I cannot 
reproduce this...

as imagedriver i use:

pecl.php.net        imagick         3.1.0RC1 (beta)

The hash is written when the gallery is created or the style 
attributes for the gallery are changed, not when the image is 
created/saved.

  so i looked where the
The hash computed for getKeyImage is there because the "stack" images 
may have a different style hash then that of the gallery. If it's 
never getting called in that method, then you are not using one of the 
"pretty" image stacks.
This might be the issue. It could be that your image backend does not 
support generating these images (so the style hash for them would 
never need to be computed). Though, if that is the case, the image 
would not have been generated to begin with...unless you changed your 
image backend from one that *does* support them (like ImageMagick) to 
one that does not (like GD).

What image driver is Horde configured to use? e.g., ImageMagick, 
Imagick, GD...?

here is my conf.php, perhaps that also helps to solve the problem

i did a little bit of basic  debugging and added some 
Horde::debug("LOG") to both methods that read and write ansel_hashes. 
i added a picture and nothing were logged. so i looked where the 
methods are called and found a place in Gallery.php -> getKeyImage() 
and here it never goes into the second if where ensureHash is called. 
so i played around with both style settings for that gallery were i 
upload my test pictures to. but no change. i only noticed that i can't 
set another preview style, after choosing another than "simple 
preview" and save and reopen properties it's still "simple preview", 
perhaps that is the problem in my case that i need to choose another 
preview style to get hashes working and than also pictures were all 
deleted.
but if this is the case that the pictures in the hash directory are 
only needed for some styles other than simple preview, than the 
question is why are they generated and saved so that they are not 
deleted when deleting a picture

this is a complete fresh install of ansel no migration from horde 3.x

It looks like this might happen when upgrading from an existing Ansel install.

Did you update from an existing Ansel install or is this a new 
install? It looks like the migration doesn't create the hash for 
existing gallery styles when upgrading...

any chance to give some hints what i have to look for when it is not 
ok that ansel_hashes is empty?

Cannot reproduce. All images are successfully removed when I delete an 
image. Having an empty ansel_hashes table, though, would definitely 
prevent images from being deleted. So we/you need to figure out why 
that table is empty...

ansel_hashes is empty and in ansel_images i can't see such a string

Do you see that hash string in Ansel's signature table?

when i delete a picture from a gallery, the picture is removed from 
full, mini and screen directory on the filesystem, but there is also a 
directory named 'c73bbb618b87e81a79e6aac7a9476a06' and there the 
picture is still present. ./ansel-garbage-collection returns only: No 
cleanup necessary.