Some UI related feedback
First of all thanks a lot for a well designed Kalendar application! Made me install KMail and the whole Akonadi stack again. After using Kalendar for a bit now I'd like to share some feedback on the data entry UI.
When you create a new event start-time is preset with the current time and end-time with an hour from now. Which is ok in cases where the event which is added starts right now. However, in the more likely case that an entry is made for a future event this always leads to the error message that end date can not be before start time. (1) This is technically correct but somewhat distracting because I didn't yet get to enter the end time. The only way around this is to start data entry with end-date and end-time and then move up to the start fields. (2)
There are different ways to handle this I think, maybe do the start>end check after the two end fields have been populated? Or leave the two end fields empty when the form is opened and fill with start-day/start-time+1h after the respective start field has been edited?
Second thing I noticed is the Timezone field (3). I was trying to come up with use cases where I would want to apply a different timezone to an event? Is this for cases where I (my computer) will be in a different timezone and also the computer time will be reset to the new timezone when the event takes place? In any case this looks like a very special use case to me which may mean that field should be at the very button of the form?