Change Desktop Background Color

[mparent]

I know how to change the background image as this is trivial using
reconstructor. Howver, I'd like to change the background color as
well. The background image I'm using has some transparent components
that I'd like to be filled with a specific color by default. I'd also
like to change the default setting for the background image to
centered instead of zoom. Is there any easy way to do these two things
with reconstructor? If there's a file to edit by hadn I'm willing to
do that as well.