Hi,

I would like to be able to cancel the close event, for weird client-requirement reasons.

It seems reasonable to make all the events cancelable. In this case of close, the code change is simple:

From:
            this._trigger( "close", event );
            this.menu.element.remove();
            this.menu = null;
To:
        if ( false !== self._trigger( "close", event ) ) {
            this.menu.element.remove();
            this.menu = null;
        }