Bug#655328: The documentation for removing background in gdm3 is missing

[jaakov at ro.ru]

That does not work.
Probably you mean

primary-color='#000000'

instead of

primary-color '#000000'

Then it works. Thanks anyway. I was really desperate and this info was 
hard to find (since months).

I correct my bug report.

It should sound this way: the documentation for removing the background 
image is missing or hard to find for non-maintainers.

Jaakov.