Line spacing too large for TTF?

[David Engster <deng@randomsample.de>]

I'm a bit confused regarding the default line spacing in Emacs.

I'm using Emacs 23.1, started with 'emacs -Q'. Then I evaluate

(ucs-insert #x2503)

which inserts the box drawing 'heavy vertical' unicode character. I
think with the default line-spacing set to 'nil', these characters
should connect when repeated in the following lines, but they
don't. With bitmap fonts, there's usually a gap of 1 pixel, and with a
TTF like 'Bitstream Vera Sans Mono', it's about 3 pixels.

I'm not sure if this is intentional or a bug? The reason I'm asking is
that when using a TTF with very small height, it seems to me that
considerable space is wasted with these spacings between the lines. For
an example, look at the left sidebar in this screenshot:

http://www.randomsample.de/minimap-ex3.jpg

I'd like this sidebar to be more 'vertically condensed'.

Regards,
David