I've also find this fix that zooms to fit all markers
LatLngList: an array of instances of latLng, for example:
// "map" is an instance of GMap3
var LatLngList = [
new google.maps.LatLng (52.537,-2.061),
new google.maps.LatLng (52.564,-2.017)
],
latlngbounds = new google.maps.LatLngBounds();
LatLngList.forEach(function(latLng){
latlngbounds.extend(latLng);
});
// or with ES6:
// for( var latLng of LatLngList)
// latlngbounds.extend(latLng);
map.setCenter(latlngbounds.getCenter());
map.fitBounds(latlngbounds);