How do you tell if mobile users are online on Facebook?

[Vegito]

My friends use there mobile phone to get on Facebook. & I've noticed that sometimes when I press the ''offline/online bar'' on the bottom right corner, it shows some mobile users but doesn't have the green light up.. then It will change and then now I would see a different set of friends pop up as if they were online or is online, but on mobile. I've also noticed that 1st mobile user on the list is has liked something or posted a status. Could this mean mobile users are online even without the green light?

[ashik]

yes! in pc u have scripts always talking to the servers in fb data center that u r online! but what use is there these scripts in a mob. that dont support them? so the fb come to know they are online by their activity in fb such as like,share,cmnt etc... and after a period of time! if user isnt liking anythng,fb servers will think they are gone and let u know they went offline
and yes it means they can be online while shown ofline.

[Debasis]

no. If nt show green light. That particulars friends r nt online. If u used mobile, so it does nt show u online.

[~o0o~]

If it doesn't show a green light, it means they are using mobile but did not go online on chat. just like me buddy.