The problem seems to be mostly gone in 6.2.73753.  I can't get a large number
of dashed lines to appear any more (tested on Solaris 10 SPARC and Solaris 9
SPARC, not on x86 yet).  There are still occasional artifacts - sometimes
a second dashed line that does not following the mouse pointer is left, but
I can't get a screenshot of it because clicking outside the estudio window
changes focus and (apparently) causes a redraw.

So the bottom line is, it is way better but not 100% gone.  I can't figure
out what causes the line to sometimes not be erased and leave a second line
that doesn't follow the mouse pointer.  Triggering of GC cycle?  Some other
event?