@jbroutier Thank you for your PR.
Can you please a test-case to justify the change?

@GeoSot I've added a test case as requested.

I've also updated the fix to check both events instead of just the mousedown one for testability purposes. Otherwise in one case I cannot trigger the event handler of the modal and in the other case I cannot reproduce the bug.

I've linted a bit, but got another idea too.
You may, instead of two contain checks, to try this

        if (this._element !== event.target || this._element !== event2.target) {
          return
        }

it should work too and it covers both cases