I forked your repo into the mantisbt-plugin organization, and granted you push access. I suggest you keep it up-to-date there instead of your personal fork.

Great!
I'm glad to help the community =)

Dentxinho, maybe you want also update the plugins wiki page
http://www.mantisbt.org/wiki/doku.php/mantisbt:mantis_plugins

http://www.mantisbt.org/wiki/doku.php/mantisbt:issueviewers

"This topic does not exist yet

You’ve followed a link to a topic that doesn’t exist yet. If permissions allow, you may create it by using the Create this page button."

Looks like I don't have permission to create page, because I can't see the button...

I created the page.

I have done some testing but the counting cannot be very accurate.
In case you view an issue and decide to assign it to someone else, you immediately have 2 views since the page is refreshed after porcessing the request. Admitted, the page is shown twice but in fact it is still the same view.
Not sure if you can use a filter to ignore such view counts.

The easiest way to exclude such kind of double counts might be to check the access time.
e.g. don't count access if the last access of the user is just n seconds before current access.
3600 seconds might be a good default to avoid getting questionable results.

Perhaps something can be used like :
if (substr($_SERVER['HTTP_REFERER'],-8) <> 'view.php'){
*** count
}