I tried Zenphoto 1.4.1 [7640] (Version officielle).
Well, it's better, but not completely fixed. Now, after cropping, the thumbnail is fine in the gallery, but not on the back-end where we can only see the default crop.
Then I click again on the "Thumbnail cropping" button again, I see the default thumbnail crop. So my cropping isn't completly saved.
Some screenshot :
1) I want my own crop : first click on "thumbnail cropping"
http://i48.servimg.com/u/f48/13/98/61/29/clipbo10.png
2) I still see the default cropping on the backend
http://i48.servimg.com/u/f48/13/98/61/29/clipbo12.png
3)so I click again on default cropping
http://i48.servimg.com/u/f48/13/98/61/29/clipbo11.png
Thanks for all.