the checked and unchecked states for a checkbox have different heights. this is a nuisance, as it makes forms reflow and move whenever ou check or uncheck. simple fix is described here - it's just a CSS problem. there are two fixes here - I'm not sure what size the checkbox was supposed to be. visually, I prefer the second (larger) appearence. in both cases, chrome/global/skin/checkbox.css is being edited 1) on line 52, change border: 1px outset #CCCCCC; to border: 1px inset #CCCCCC; this outset border takes up space in the box that isn't there, forcing the box to enlarge. 2) on lines 30 and 31, change width: 8px; height: 8px; to width: 10px; height: 10px; this is because there is an inset border in the active state, which makes the 8pixel image need a 10pixel box. I prefer the larger checkboxes of the latter fix.

I don't see any reflow in the page when the checkboxes are toggled. It's true that the :active state gives the appearance of "larger" as the transition occurred, but that is part of the visual feedback ... the external dimensions of the <checkbox> do not actually increase. But, this is Ben's domain (and I may be clueless here :-]).

in the internet search panel (at least) they cause everything to move down. I think in prefs the text is taller than the buttons and therefore they don't cause an unwanted reflow.

Move to M20 target milestone.

Ben made this change, I do believe (and, for the record, I am clueless). (Or actually, he made the second of the two proposed changes; in the first case, whether inset or outset, the border does not take more room.)