jSpreadsheet CE custom tooltip on hover

I am trying to set up custom tooltips for column headers. While the pro vers. site describes how to do this, I could not find the information on the CE site. I tried the following, but the column title appears in the tooltip.

jspreadsheet(document.getElementById('spreadsheet'), {
    workshets: [{
        columns: [
            {
                type: 'text',
                title: 'MyTitle',
                tooltip: 'This is a custom tooltip',
                width: 160
            }
        ]
    }]
});