[PATCH 0/3] gitk: improve dark background

The gitk preferences allow for the user to select different colors.
The setui is even set to dynamically detect how light or dark the
background is and set the selection color to be the opposite, but
there are a few other color selections that don't currently work with
a dark background such as the black outlines.  This patch improves the
color selection.  In some cases it just needs to use the current
forground color, other places it is more complicated.

The gitk_colors branch can be pulled from,
git://gitorious.org/~dfries/git/dfriess-git-mainline.git

my relevant .gitk config file settings,

set mainfont {Helvetica 8}
set textfont {Courier 8}
set uifont {Helvetica 9 bold}
set uicolor grey85
set bgcolor black
set fgcolor white
set colors {green red blue magenta darkgrey brown orange}
set diffcolors {red green cyan}
set markbgcolor #404060
set selectbgcolor gray50