Martin,
I went to a demo of the Google Maps API and found this demo:
http://gmaps-samples-v3.googlecode.com/svn/trunk/geocoder/v3-geocoder-tool.html#q%3D42.032974%2C-90.703125
You should see the InfoWindow square.
I looked under the hood and found the code below, maybe the border of your window. Hope this helps.
var openInfoWindow = function(resultNum, result, marker) { return function() { if (selected != null) { document.getElementById('p' + selected).style.backgroundColor = "white"; clearBoundsOverlays(); } map.fitBounds(result.geometry.viewport); infowindow.setContent(getAddressComponentsHtml(result.address_components)); infowindow.open(map, marker); if (result.geometry.bounds) { boundsOverlay = new google.maps.Rectangle({ 'bounds': result.geometry.bounds, 'strokeColor': '#ff0000', 'strokeOpacity': 1.0, 'strokeWeight': 2.0, 'fillOpacity': 0.0 }); boundsOverlay.setMap(map); google.maps.event.addListener(boundsOverlay, 'click', onClickCallback); document.getElementById('boundsLegend').style.display = 'block'; } else { boundsOverlay = null; } viewportOverlay = new google.maps.Rectangle({ 'bounds': result.geometry.viewport, 'strokeColor': '#0000ff', 'strokeOpacity': 1.0, 'strokeWeight': 2.0, 'fillOpacity': 0.0 }); viewportOverlay.setMap(map); google.maps.event.addListener(viewportOverlay, 'click', onClickCallback); document.getElementById('viewportLegend').style.display = 'block'; document.getElementById('p' + resultNum).style.backgroundColor = "#eeeeff"; document.getElementById('matches').scrollTop = document.getElementById('p' + resultNum).offsetTop - document.getElementById('matches').offsetTop; selected = resultNum; } }
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