First, thank you for this idea of time management that has great potential I think.

I nevertheless encounter a problem with my drupal version ( Date popup + date API 6x.2.7, Chaos tool 6x.1.8, jquery UI 1.6, jquery update 1.3.2):
When trying to check some marks, first check is working.
Then each new check cancel the last, so I can only get one mark saved !
I suspect this might be a problem with jquery but I am not sure.
I'v also tried holding down CTRL, SHIFT but nothing works.

Any idea ?
Thanks in advance, it would be really great to have this working