During a split second we see some garbage on the screen on
desktop systems that don't have UPSes. Better to grow than to
shrink (though we shouldn't do either), so start with the battery
information hidden.
Add mnemonics to all items. We may need to revisit this and set
labeled-by relations for the combo boxes where the labels are
checkboxes (in that case, the mnemonic automatism doesn't really
work, I think).
Part of bug 650132
