Change GDM background color to match your GDM theme (applies to Xfce)

Please read the Launchpad bug report where the issue was raised.

At the bottom of /etc/gdm/PreSession/Default change :

 # Default value
        if [ "x$BACKCOLOR" = "x" ]; then
                BACKCOLOR="#dab082"
        fi

to:

 # Default value
        if [ "x$BACKCOLOR" = "x" ]; then
                BACKCOLOR="x"
        fi

Where #dab082 is the default brown color that appears right after GDM exits and before the desktop files are loaded. Works nicely with Xfce here.

Edit: from the bug report, the bug is fixed in Hardy :)