I wrote:
At http://naturalhistory.museumwales.ac.uk/sharpshooters/ two of the image tags specify a size for one dimension, giving it as 100%. When one dimension is auto and the other is percentage, it doesn't scale properly.
I see that calculation using percentage has to be in textblock because it uses availWidth or availHeight, so... is there a deep need to keep the auto/abs case in Image's sizeRequestImpl instead of Textblock's calcWidgetSize?
I was just playing with adding all of the cases to calcWidgetSize and it looked like it was working except that an unloaded image with, e.g., height=100% alt=whatever would end up ridiculously wide because height_of_page / height_of_alt_text * width_of_alt_text is a large number.
I eventually ran into a page where simplemindedly taking, say, width=50% and expanding the height accordingly was bad. It had an <hr>. Hmph. Web browsers are too complicated; let's make something easy instead :)