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Info on upgrading to v4
unselectCancel
A way to specify elements that will ignore the unselectAuto option.
String, default: ''
Clicking on elements that match this jQuery selector will prevent the current selection from being cleared (due to the unselectAuto option).
This option is useful if you have a “Create an event” form that shows up in response to the user making a selection. When the user clicks on this form, you probably don’t want to the current selection to go away. Thus, you should add a class to your form such as “my-form”, and set the unselectCancel option to ".my-form".