List line height, row shading, and selection position

If you use an installed font and the List component, there's a problem with alternate-row shading and item highlighting. Check this out:



For all examples, the selected (highlighted) item is supposed to be "Theta". The font is Adobe's Helvetica Rounded, but any font other than the default Comic Sans can cause an offset. It looks like line height in List is not keyed to the actual height of the font -- in this case, it assumes something taller than what's installed. Aside from the alternate-row shading misalignment, selected item highlighting becomes pretty much guesswork. In the first example, if you set the selected row to "Sigma" instead of "Theta" the highlighting is shoved down so far that it doesn't even show on the list.

This issue first came up five months ago (selected_list_item_mis_positioning) and seemed to be solved by a one-pixel tweak. But it looks like that fix was Comic Sans specific, instead of dealing with a deeper font awareness problem.