Windows XP Home SP1

java version "1.4.1-rc"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.1-rc-b19)
Java HotSpot(TM) Client VM (build 1.4.1-rc-b19, mixed mode)

I have a JList in a JScrollPane. I'm trying to get it to scroll to the
latest item added (i.e., the bottom of the list) after each line is added.
So I tried using ensureIndexIsVisible(). The problem is, doing that causes
corruption - some of the text is rendered OUTSIDE of the JList, off the
bottom. If that spurious writing is covered by another window and then
uncovered, causing a repaint (no new lines added to the list in between),
the spurious writing doesn't come back, as expected.

I also tried instead grabbing the vertical scrollbar from the scroll pane
and setting its value to the maximum, thus also scrolling to the bottom; it
had the same weird effect.

I have a GIF (which I can't post here) that clearly shows the writing being
scribbled below the limit of the box, and can explain the problem better
than words. If anyone has an urge to see it, e-mail me privately.

Any ideas why this happens? It happens repeatedly, not just a one-off fluke.

Any other suggestions of how I might get this list scrolled to the bottom
each time? I'm actually trying to make a log output window, where outgoing
commands are one colour and incoming responses are another, which is why I
want it always showing the last line logged. If I use a JTextArea, it works
fine, but I can't get the colours. I tried using a JEditorPane to use
text/html for the colours but that was horribly jerky and blinky (yes, I'm
inventing "blinky" as a word). A JList with custom rendering gives the
colours great, and doesn't jerk or blink... but this scrolling is the last
hurdle.