html2canvas offscreen

In using html2canvas, I have a stack of DOM objects (relative positioned div's that contain various things), that I wish to create individual thumbnails for. So if there are ten divs, I will create ten thumbnails.

Some of these objects will be offscreen --each of these divs are in a single, encompassing div called "mainDiv". I iterate through the divs within mainDiv and execute the html2canvas on each of them individually.

For those that are onscreen, this works fine. Those that are offscreen do not -- they come back blank. I created a workaround that scrolls the objects to the top of the mainDiv, however this is a kludge and visually unappealing.

Is it possible to specify a DOM object that is not visible? Ideally, I'd like to be able to specify a containing div and have html2canvas ignore the parent visibility, so I can screen capture hidden objects, but barring that, I'd like to be able to screen capture objects that are simply scrolled off screen.

Any thoughts, ideas? Thanks!

---- Here is some example code. Basically, if you had a bunch of divs within a div, iterate through them. I actually do this recursively so that only one gets processed at a time, with the callback calling the recursive function, so it looks something like this:

  function recurser(anIndex, callback) {
    if (anIndex == -1) {
        callback();
        return;
    }
    $(myDivs[anIndex]).html2canvas({
        onrendered : function(canvas) {
            var img = canvas.toDataURL();
            // store the image in an array, do stuff with it, etc.
            recurser(--anIndex, callback);

        }
    })

}

Once the recursive calls are complete, it executes the callback function, which is a function that will do stuff with the images.

Again, all this works fine as long as the objects are visible within the scrolling div that contains all of the divs