Inhibiting "This balloon may be using incorrectly formatted image URLs"

[schreyerplace]

I have a KMZ defining thousands of placemarks. Each placemark has a balloon that contains a description with an image tag that points to a remote resource providing an image specific to the placemark.  The external resource providing the images is not under my control (I'm building a demo of capabilities within a very large enterprise and using resources from another group within the organization).

There are many situations when no image is available for the placemark and a 404 is returned. I'd like to substituted a default "Image Not Found" image in these situations.

I've coded the image tag in various formats but this form seems the most consistent:

<img width="230" height="173" src="files/NoImageAvailable.png" onerror="this.src='files/NoImageAvailable.png'" onload="this.src='http://blah.blah.blah.net/files/Photos/XYZ.jpg'" />

By default the src= image is the not available image. This seems necessary to consistently end up with an image in all situations. The onload function attempts to assign the correct image from the remote resource. If that attempt fails, the onerror function assigns the locally packaged not available image.

I consistently get the appropriate visual behavior with one caveat; the top of the balloon contains a yellow background div proclaiming:

"This balloon may be using incorrectly formatted image URLs"

Since I'm handling the error appropriately myself and everything is working fine, is there a way to inhibit this automatically inserted warning?

I'm loading my kmz into 6.0.1 on Mac directly from the file system.

Thanks.