Since the progress bar on the UpdaterFrame is only updated after each file is 
extracted and copied, it does not appear to move smoothly at all when the 
package have one or two large file.

The proposed patch is to move the progress bar update into copyStreams() method 
where we update it on event interval (every time we check for cancel).   The 
result is very good.   The patch I attach may not be the best way to achieve 
this, but I think one way or another, it would be worthwhile to make the 
progress bar move smoothly regardless what is in the package.

Thanks,
Jun