Trigger eventTimesChanged on cell change

[Leccho]

Describe the solution you'd like

I would like the eventTimesChanged to be triggered every time you add or remove a cell of the selection, instead of only triggering the event once the mouse button is release.

Describe your use case for implementing this feature

This would allow to update the event view live. For exemple updating the time of the event:

[matts-bot]

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