Hello,
I was making a new template/site with your component when i noticed that, after saving it, some .php file in the joomla main directory is chmod to 777.
I noticed it because bluehost, my hosting, doesn't allow to chmod to 777 for security reasons and it was showing a blank page instead. Can you confirm this issue? Is this a bug?

UPDATE
I've tried just deleting a site and it chmod my files in joomla home dir to 777 also.

Thank you.

JMS use the permission right that you have setup in the "multisites.cfg.php" file.
See user manual page 14.

By default this file contain 755 permission.

If you are using the Joomla FTP layer, the the permission is the one attached to the FTP user. If this is the case, check the permission attached to the FTP User.

Hello,
I've checked the file multisites.cfg.php, it says 0755. The ftp layer in joomla is disabled, but i'm still having this problem.

You can search everywhere in multisites and we never we do a chmod 777.

Perhaps there is something else (perhaps a plugin) that modify the directory

I have no idea, i don't have any plugin installed (only cssjscompress but it wasn't enabled).
The fact that this happens when i add or delete one site from manage site let me think that there is something with jms multisite.

Update:
It seems that this not happens always.
How do i reproduce it: Add a new site, random name, choose a random template from my list, insert random db data (name/user), save it. Delete it and there is some file chmod to 777.

I don't know if this is related:
When i add a new site i receive some error (4-5) saying it couldn't make some symbolic link, but it works, i haven't other problems. These files are not joomla file, but bluehost files.. 400.shtml and so on.

It may not work when you have error during the website creation.
The JMS index is not updated and therefore your new slave sites may not be defined.

So if you have some Symbolic Link that can not be create, either modify the JMS templates to ignore them or fix the issue until you have a success. Otherwise some processing are not performed.