Hi all,
I've searched for a solution for a very simple problem but, so far, I
haven't been able to find it, so here it goes the problem:

I created a JComponent-derived object, called Graph, which basically
draws a graph in its paint(Graphics g) method.

I show this Graph object within a JScrollPane, which is in a JFrame
together with other controls. One of them, a JSlide, controls the size
of the Graph object (a zoom).

Almost everything works well: when sliding the JSlider its
ChangeListener calls a method in the Graph to change its PreferredSize
and calls repaint(). The Graph works as expected in response to the JSlider.
However, the JScrollPane and its viewport do not get affected by the
change in size of the Graph object until I resize the whole JFrame, thus
I cannot use the JScrollPane bars to navigate through the whole Graph
unless I resize the JFrame (which obviously it's not the desired
behaviour). When reducing the Graph the viewport does not get reduced
either, so I get a huge ScrollBar for a tiny Graph...

I have tryed calling repaint() over all the elements (JFrame,
JScrollPane, its viewport), and revalidate() over them, but humbly I
have to say I don't know how to solve it....

thanks in advance for any suggestion.

Sergio