Googe Maps API - Callback

Hello everybody,

I'd like to integrat the Google Maps API.
Therefore I used the sample Google Maps component.

But the samples don't work like it should.
Somtime the map is displayed and sometimes not.
I'm pretty sure it dues to the missing callback. The init function starts before the google api is downloaded.
Fortunately the google API provides an callback (https://maps.googleapis.com/maps/api/js?key=YOUR_API_KEY&callback=initMap).
How can I access the callback in design studio?

If I create the function like always in the component.js file, it is not found.

Thanks a lot

Robert Gründer