function placeElementOnScreenCenter(element)
{
	dimensions = elementDimensions(element);
	position_x = document.documentElement.clientWidth/2 - dimensions.w/2;
	position_y = document.documentElement.clientHeight/2 + document.documentElement.scrollTop - dimensions.h/2;
	element.style.position = "absolute";
	element.style.left = position_x + 'px';
	element.style.top = position_y + 'px';
}

function placeElementAtMousePointer(element, mouse_event, offset_x, offset_y)
{
	scrollY = window.pageYOffset?window.pageYOffset:document.documentElement.scrollTop;
	scrollX = window.pageXOffset?window.pageXOffset:document.documentElement.scrollLeft;
    element.style.position = 'absolute';
	position_x = mouse_event.clientX + scrollX + offset_x;
	position_y = mouse_event.clientY + scrollY + offset_y;
	element.style.left=position_x + "px";
	element.style.top=position_y + "px";
}