Comment 10 for bug 1531913

The intention was that a scope can specify a specific fallback image. That image should be shown when the normal image load returns an error or an empty image (zero-length ByteArray, or whatever type it is).

This allows the scope to specify a specific fallback image that might be needed to keep style/theming for the scope. If the scope doesn't provide a fallback image, or loading of the specified fallback image fails, the shell can substitute some generic fallback image.

That was the thinking at the time we added this feature.

What's the problem with doc? If it isn't right, I'll fix it.