Big text field: WAI checks: resize the incorrect images automatically

I selected one of my (large) image through the FCK built-in image picker and resized it in FCK to a smaller size. WAI checks are turned on.

When switching to another field (I was updating an existing container), this suddently redisplay the WAI error but with the image at full max size.

Only the thumb should be displayed here (or at least a reduced image even if the full image is loaded).