@Achim W.
thanks for reply. i always do kill my jdownloader process, i use this command to specify jdownloader process id number

ps -ef | grep -i jdownloader | grep -v grep

then use
kill -9 PID
to kill only jdownloader
but do this procedure really update jdownloader ? how can i tell?. for the vnc i don't like this idea for servers .

@mrc
thanks for creating the ticket