The initial beta versions of GMaps apparently had cross-browser compatibility issues – primarily for users of Internet Explorer. Hopefully someday soon those using IE will realize how superior Firefox is and switch over (You can always download FF from this site. ). Anyway, the intial code, had an icon size of 12x20and then a subsequent release omitted the size all together. My initial testing didn’t reveal issues under IE. Users did report the problem and seemed to be more persistent. In addition, I rewrote the rendering class to utilize the GMarkerManager class for efficient rendering when users have a large number of markers on a map.
In the process of rewriting the rendering class, it became VERY apparent that I needed a mechanism to manage the icons and for users to specify their dimensions. This, unfortunately, is a bit more difficult to manage but does provide greater flexibility so you can use your own icons. So far, it appears to also solve the IE problem.