First of all, thank you for this. It made things better. New comments are inline.
These are the results:
1) In folders list the multibyte characters are cut (... is put in the middle of the string) incorrectly. This happened before, I just didn't mention it to the dev list until now. This means that the PHP function should check the length of string as multibyte and cut it as such. Currently I have folders that have AAA?...AAAAA (where AAA=multibyte chars). The question mark (?) is shown because the second byte of the character is cut so it's substituted by ? (therefore I assume that the PHP fuctions do not treat this string as multibyte before checking/converting/minimizing length). There are multibyte folder name with real length of 8 chars that are cut and English folders that are 10 or more and are not cut. So perhaps this behaviour should be examined.
2) When I use English GB language the folders work nicely. They used to work nicely on the folder list (ie show), now the create/rename folder works flawlessly too (big thanks).
But when I use another language, for example Spanish, things get messed up, just like in the past. Let me know if I am allowed to send you screenshots (via personal email) to show what happens when charset is not ISO-8859-1, or perhaps a login account on such a mailbox.
Results (for non English charset):
Create folder -> "error occured while creating folder" or similar error in the translated language
View folder -> strange charset conversion (or no conversion at all?) is shown instead of the normal folder
Rename folder -> "error occured while creating folder" or similar error in the translated language
I have noticed that the erratic folder behavior happens when I use specific languages like
Slovak, Polski, Greek, Espanol, Arabic etc but not on Japanese, Russian, English (it works fine on those showing always the correct folder names as intended)
Finally, I am using PHP 4.4.x branch to test.
Let me know how I can help further to solve this.
Your support is very much appreciated,
Eric