I recently upgraded JDK from 1.5.0_10 to 1.6.0 (that's Sun's JDK in each case,
on Windows XP), and since then have noticed an odd graphical glitch with the
"red wavy lines" error highlighting in the Netbeans editor.  As I move the
cursor down the page, the red lines above the pale yellow hightlighted line are
not redrawn properly, thus becoming red dotted lines instead of wavy ones.  If I
switch to a different tab then back again, they are redrawn correctly.  When I
then cursor back up the page, the line above the current one shows the same
glitch in the red lines, but the one below it is redrawn correctly each time as
I step up the page.

I tried upgrading from Netbeans 5.0 to 5.5 in case it was already fixed in the
newer version, but that behaves the same.  If I switch back to using JDK 1.5
using "netbeans --jdkhome ..." with either version then I don't see this
behaviour, the wavy lines stay the same wherever I move the cursor.

Hope that description is clear enough.  I'll attach a flash animation so you can
see exactly what I mean.