I found some things to change with this.
1.Calendar shouldn’t let user select improper definition of interval. So you can select for example month, without choosing interval. For example you can generate interval like this: ; BYMONTH=1. You must check calendar functions.
2.Other thing is that there could be posibility to muliti select jobs, for example to
drop, modify interval, action…
3.Another option to stop job.
4.Posibility of purge logs.
5.Auto refresh with specified interval.
6.Afther save changed job parameters, buttons should be refreshed, without clicking on job in list window (for example RUN button).
If I will find some more improvement , then give a sign.