Who deleted my screenshot?

This error will show up only, if I'm not logged in. Otherwise it shows "15:21" for my "Time difference" posting. (Depending on my "Time difference" user setting.)

I don't really understand what you mean. How many days/hours/minutes ago a message was posted is completely independent from the time zone.

In my user settings I have a time difference of "1" (hour). Let's say I post a message at 14:00 local time. I come back after 5 minutes. If I'm logged in, the message will be shown correctly with 14:00 and "Latest postings" shows "5 minutes ago". Then I log out and now the message is shown as 13:00, but "Latest postings" still shows "5 minutes ago". That's confusing! At least to me.

To be honest, I never fully understood the timezone stuff.

Here is an explanation.

I know those pages, but ... To make things even more complicated, they invented the stupid DST stuff.