Agenda: Changing time in an event form changes the wrong time

[ywarnier]

There are issues with the agenda component we use in 2.0 for the selection of start/end time (not date).
When creating a new event, it is by default set to run from 00:00 to 23:59 the same day that we clicked in the calendar view.
But if I then want to change the end time and I click on the end time and then change the time below the dates selector, it's the start date that changes, and it becomes impossible to either change the start date or change the end date.