window offset, not doc offset
the GUI is horizontally-divided into 4 vertical sections, each of which loads its own document, similar to a dashboard. A function call from one of the center documents' controls triggers a layer to cover the screen (for modal purposes) and places a control in its center where the user interacts until closed.
Problem is that css properties position, offset, top and left are all relative to the document, and not to the window. Result is that the modal covers only the one vertical section and not the entire screen.
I have attempted to get around the issue by adding $(verticalDocNode).offset() to the mathematical equation, but an alert reveals that instead of a coordinates it returns [object Object].
I should note here that the page does not contain any iframes.
How can I best implement a full-screen modal?