These docs are for an old release. Info on upgrading to v5
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eventStartEditable

Allow events’ start times to be editable through dragging.

Boolean, default: true

You must enable the interaction plugin before using this setting. See code samples on the editable article »

This option can be overridden on a per-source basis with the startEditable Event Source Object option or on a per-event basis with the startEditable Event Object option.