// Center a positionable element whose name is passed as 
// a parameter in the current window/frame, and show it
function centerOnWindow(elemID) {
    // 'obj' is the positionable object
    var obj = getRawObject(elemID);
    // window scroll factors
    var scrollX = 0, scrollY = 0;
    if (document.body && typeof document.body.scrollTop != "undefined") {
        scrollX += document.body.scrollLeft;
        scrollY += document.body.scrollTop;
        if (document.body.parentNode && 
            typeof document.body.parentNode.scrollTop != "undefined") {
            scrollX += document.body.parentNode.scrollLeft;
            scrollY += document.body.parentNode.scrollTop;
        }
    } else if (typeof window.pageXOffset != "undefined") {
        scrollX += window.pageXOffset;
        scrollY += window.pageYOffset;
    }
    var x = Math.round((getInsideWindowWidth()/2) - 
        (getObjectWidth(obj)/2)) + scrollX;
    var y = Math.round((getInsideWindowHeight()/2) - 
        (getObjectHeight(obj)/2)) + scrollY;
    shiftTo(obj, x, y);
}


// Return the available content height space in browser window
function getInsideWindowHeight() {
    if (window.innerHeight) {
        return window.innerHeight;
    } else if (isIE6CSS) {
        // measure the html element's clientHeight
        return document.body.parentElement.clientHeight;
    } else if (document.body && document.body.clientHeight) {
        return document.body.clientHeight;
    }
    return 0;
}

// Special handling for CSS-P redraw bug in Navigator 4
function handleResize() {
    if (isNN4) {
        // causes extra redraw, but must do it to get banner object color drawn
        location.reload();
    } else {
        centerOnWindow("about");
    }
}
// Keep centered during scroll
function handleScroll() {
    centerOnWindow("about");
}

window.onresize = handleResize;
window.onscroll = handleScroll;