If you mean the map originally loads while its container is hidden, and then when it is revealed the maps is displaying incorrectly, what you need to do is add a callback to resize and recenter the map the first time it is revealed.
Basically, set a callback for your show event that calls
function(){
google.maps.event.trigger(map, "resize");
map.setCenter(latlng);
}
You'll need to have the map object to manipulate of course, which means you'll want to draw the map via the API if you're not already 
