The HIG currently says that:
"Using "white" or blank spacing and indentation to delineate groups is cleaner
and preferable to using graphical separators such as frames."

However, when using a high contrast theme, this can result in bugs such as bug
140836, which was caused by the HIG-conformity patch in bug 132570.

So what should the HIG spacing advice be? I think most users and visual
designers concur that, for regular themes, space is usually better than frames.
Should we perhaps recommend separating groups by borderless frames, and have the
high contrast theme engine always draw frames with a border?  Or is there a
better solution?