I could not find any documentation, hence I ask here at the forums:

How can I crop and then losslessly save in Xee?

Xee is advertised with "Losslessy rotate and crop JPEG images".
When I rotate the image, Xee allows me to use "Menu > Save Losslessy".
But when I start the crop tool and apply it, Xee makes the "Save losslessly" menu inactive.

According to my understanding of JPEG, lossless crop&save would require me to cut along the "JPEG MCU block lines" and not through them, as the outer blocks would then need recoding.

I tried whether there is a modifier key, that helps me to snap the cropping lines along the block lines, but neither ALT, SHIFT or CMD helped.