I have a tree view that is being used as the old clist, i.e., it just is
a list selection.  The items are GtkCellRendererText.

IMHO, the lines are much too far apart.  Someone (gtk+?  pango?) seems to
leave room for lots of accents, decenders, and then a little extra space,
just in case.  If the lines just consist of, say, numbers then that's a lot
of blank space.

I would like to way of squeezing the lines somewhat.