A bar must be full-screen-width (or height, for vertical bars) to
have an "exclusive zone", otherwise it appears on top of other windows
instead of moving them out of the way. To right-justify (or bottom-
justify) the indicators in a bar, add :gravity :end to its options
Am *probably* going to get rid of this again, in favour of adding
support for "spacers" in the bar - then the same bar could contain
both left- and right-justified indicators
use highest common factor of requested intervals. this will still
suck if we have e.g. intervals of 333 and 1000, we could probably
refine it a bit. no interval over 3s cares about millisecond precision
