in ImageBox.loadImage(), the captiontext argument is being ignored because the function (erroneously?) accesses global variable captionText, which is set in ImageBox.start(). this prevents the user from extending ImageBox.loadImage() to use custom caption text, which is a very common request. this trivial typo fix could allow the user to create a wrapper that could load more complex captions for images instead of just the title attribute from the element.