ink_rect and logical_rect; bug or feature?

[Darin Adler <darin bentspoon com>]

When I get the ink_rect for my layout with pango_layout_get_pixel_extents, I
get something like this (x,y width,height):

    40,-11 104,11

And the logical_rect for the same layout is:

    40,0 104,18

What does this mean? I'm assuming that a -11 for the y coordinate of the ink
rect means that the topmost text pixel is 11 pixels above the baseline. But
what does the 0 for the y coordinate of the logical rect mean? How far from
the baseline is the top of the logical rect?

(Also, please scold me and tell me what list I should really be asking this
question on.)

    -- Darin