Since, the filter button is replaced with a different button
after click, the `current_focus_elem` points at incorrect
element. `revive_current_focus` follows a good
method to locate the filter button, hence
we use it to correct the element `current_focus_elem` points at.
d779a1c tweaked `get_full_datetime` to return a string instead
of a {date, time} object. This function is used for recent topics
too but wasn't fixed to use the string.
This resulted in showing 'undefined undefined' in tooltip.
We split recent_topics module into recent_topics_(ui + data + util).
This allows us to reduce cyclical dependencies which were
created due to large list of imports in recent topics. Also, this
refactor on its own makes sense.