[xwiki-users] Timezone preference - what does it do?

I've got a bunch of objects with date fields in. When I view the page in edit objects mode, the dates are displayed with no timezone information. If I change the timezone in my preferences pane, it doesn't change the time that's displayed at all. I would expect that if there's no timezone information displayed against a time, then it must be showing me the time converted into my configured timezone. But apparently not. I'm not sure what those times actually mean now. If changing the timezone doesn't affect how times are displayed, what does it affect? This is version 4.4.1, by the way.