If u try ti run it, you will find if the inner container is
set the same width as the outer container, it's child will extend
itself, but if u set the inner container 1 pixel wider than the
outer container, it won't be extended.
If the inner container has a width 1 pixel greater than the
outer container, it is expected that a horizontal scrollbar will be
displayed. The presence of the horizontal scrollbar make it
necessary to display a vertical scrollbar, as seen by this line of
code, which eliminates the vertical scrollbar:
what I concerned is not the scroll bar, but the image.
the 1st is displayed with full size, which means the
container -- vbox -- was extended, while the 2nd image was
truncated by the vbox(even if you scroll down, you can't see the
here is the preview