I have since updated the block to allow the Administrator to see how many visible and invisible users are currently accessing the Moodle site. A teacher who is not an Site administrator, but is teacher of the course and also a course administrator can also be given the same privileges. Take for example, the image below:
A Student user who has gone invisible
Here we find that Mr Smiley Face is a student who has opted to make himself invisible. He is able to see other students' avatars as long as they did not themselves choose to be invisible.
Image 1: One invisible lurker
and one visible user.
and one visible user.
Mr Smiley Face student does not, however, know how many lurkers exist on the Moodle coursepage site. For all he knows, he might be the only lurker around. Or, he could be one of ten others lurking around the site.
The all-seeing eye of the Administrator
Unbeknownst to him, the Administrator, Frankie Kam, logged in a few minutes after him. As the Administrator, the Online Users block gives me special information, of which only users of Administrator roles and statuses are privy to, which is the number of invisible users currently logged onto the site. In the example, below, I can read the text "(1 users in the last 10 minutes, 2 invisible users)". So who are the two invisible users,you may ask? Well in this example, they are Frankie Kam and Mr. Smiley Face student. Both their avatars have correctly disappeared from the Online Users block. See the image below:
Image 2: Two invisible users and one visible user.
But the Administrator (who is also invisible) sees everyone!
You can download my Moodle 1.9.15 online_users_block.php file from here. It contains the modifications that allow a user to set himself or herself as invisible, AND to allow the Administrator to view the number of invisible users. Please backup your original PHP file first!
So, would this modification and adaptation of the popular Online Users block be useful for you, as an administrator or as a Course Teacher with Course Administrator rights? If so, how? Please share with me and others what you think about this latest development of the Online Users block.