Add loading wheel when "creating" or "updating" an event or group
It was great to have such wheel added to the pages when they were loaded !1011 (merged) It's still missing when clicking on "update" or "create" on events and groups, whereas those actions take several seconds to run. I also noticed that some users are not patient and end up creating several time the same event by clicking on the same button several times. Having a loading wheel would be a great improvement.