It would be nice when can filter in activities list by "no teacher" and "no students".
This is a good suggestion, I added in the TODO.
Until it may be solved, you could enter "Activity planning" and click "Pseudo-activities". This will list the activities without teachers and/or students sets.
Activity planning? Hm, this is a very good and useful feature :)
Only a suggestion to this: save the checkboxes state (I should click every time on "Swap axes", "Add activity",...).
OK, I also added this in the TODO. Please forgive me that I cannot do all the suggestions right away, but ... :-)
No problem :) It's only a suggestion. I can live (and use FET) without this but it will be comfortable (me and I think, another people too).