Google Maps: How to create a custom InfoWindow?

Question

I just came across http://fwix.com/

I really like how they create the InfoWindow (popup) when you click on a map marker because the corners on their InfoWindow are not as round as the default InfoWindow corners.

Question: How do they create their InfoWindow so square, which I like, because the default Google Maps InfoWindow for a map marker is very round.

UPDATE:

Here is a screenshot of what I'm talking about:

Answer 1

I'm not sure how FWIX.com is doing it specifically, but I'd wager they are using Custom Overlays.

Answer 2

EDIT After some hunting around, this seems to be the best option:

http://google-maps-utility-library-v3.googlecode.com/svn/trunk/infobubble/examples/example.html

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Google provide a demo that shows how to implement a custom info window. It requires a fair amount of code, but seems to be pretty straightforward.

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There are some more examples using the Google Maps Utility Library (v3) Styled Marker extension. They definitely don't look as nice as the example in your screenshot, however.