=> {
        const b = e.dataTransfer.effectAllowed;
        e.dataTransfer.dropEffect = ('move' === b || 'linkMove' === b ||
                'copyMove' === b) ? 'move' : 'copy';
        // console.log('drag over');
        return cancel(e);
    });
    document.body.addEventListener('dragenter', e => {
        elm.ports.dragOver.send(true);
        return cancel(e);
    });
    document.body.addEventListener('dragleave', e => {
        elm.ports.dragOver.send(false);
        return cancel(e);
    });
    d