[Plugin: Woocommerce] limit image by height

I have spent weeks on this problem, read hundreds of posts and pages,experimented using 3 test sites.
How do I get woocommerce to obey the resize settings and limit the image to either width or height, whichever side is the longer?
I have run Regenerate Thumbnails 50-100 times, also used Force Regenerate Thumbnails
I ‘Inspect Element’ or use Firebug and I can see the image being used and its exact size.
I have 1500 products from a previous shop, mainly the sizes are portrait and various sizes.
I want to limit the images by height, NOT width.
Woocommerrce settings uses the width setting number as the width and the height just goes by the same ratio – so I get images 100px wide and 300px tall, 100px wide and 400px tall etc
I am using latest Woocommerce and WordPress.
In Woocommerce>settings>product>display there are width and height boxes, but the height box is ignored.
I would like to set Single Product Images at 240×240 and have the images longest side be limited to 240. Catalog images 100 wide by 100 tall and have the image fit that box.
Why is Woocommerce ignoring the height setting in the height box?
How can I fix this problem?