How to add an info window to the Google Maps Block?

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I'm using the default Google Map block installed in concrete5 (5.6.1.2). All works fine, but there is just one thing I miss: an option to enable an info window above the marker. I've tried editing the controller file using the javascript provided on the Google Maps API page to see if it works, but it doesn't work. Is there a way to enable this, like placing the info window code in the header of the page?