Speaking of the login form....

In the file: inc/js/jquery.dolPopup.js

If you change:

if (o.fog && !$('#dolPopupFog').length) {
$('<div id="dolPopupFog" style="display: none;">&nbsp;</div>')
.prependTo('body')
.css({
position: 'fixed',
top: 0,
left: 0,
width: $(window).width(),
height: $(window).height(),
see more opacity: o.fog.opacity,
backgroundColor: o.fog.color,
zIndex: 999
});
}

TO:

if (o.fog && !$('#dolPopupFog').length) {
$('<div id="dolPopupFog" style="display: none; background-color:#000000;">&nbsp;</div>')
.prependTo('body')
.css({
position: 'fixed',
top: 0,
left: 0,
width: $(window).width(),
height: $(window).height(),
opacity: .8,
// opacity: o.fog.opacity,
// backgroundColor: o.fog.color,
zIndex: 999
});
}


....then you can have control over the background behind the login box. I made this change because I have a dark image tiled on my pages and I wanted the background to turn darker, instead of white.

I commented out the existing lines. I hard coded the opacity. Then I added the background-color style element to the dolPopupFog div.

When I first did this, there was no way to change it in css, so that's why the changes to js. You just have to remember to make the changes after an upgrade.

Then, to change the backgound behind the popup login box, just change the background color of the dolPopupFog div. Change the opacity to any value between 0 and 1.