Dialog: overlay: absolute positioning without theme

[svermillion]

Fixes #7917. This positioning shouldn't be left up to the theme's css.

[scottgonzalez]

How is this the problem and why can't it be fixed in the stylesheet?

[svermillion]

Without it, the overlay is added to the bottom of the page at a height that is approximately equal to the client viewport height an incorrect width (a bit wider than the client viewport). This is undesirable beyond the point of style:

1.) The modal dialog isn't truly modal since the overlay does not actually overlay the page's content and still allows, at the very least, mouseover events definitely still fire in the page.
2.) It drastically alters the page layout, making it about twice the height and wider, causing both scroll bars to appear and/or increase noticeably.

I'm not sure where the line is typically drawn in jQueryUI in regards to style vs. function, but this seems firmly on the function side.

[scottgonzalez]

.ui-wdget-overlay is already absolutely positioned form jquery.ui.core.css. I don't see how your change helps.

[svermillion]

It would fix modal for people not using the themes, which is how this ticket likely came about and how I have noticed it myself. It seems weird to me that modal = true breaks if you don't use the official themes, but maybe that is a normal/acceptable caveat to going custom on style. If so, I think the associated ticket should be closed as "won't fix".

[scottgonzalez]

That's an invalid use of jQuery UI. Our functional CSS is required, our theme CSS is not. I've asked the original reporter of the ticket to provide a reduced test case so we can see if he's not including the core CSS (he's clearly using the base theme in the screenshots).

[svermillion]

Wow, my bad. My apologies.