Max Width and Max Height doesn't work correctly, and they certainly don't work together with the selected image stretch mode.
Max Width and Max Height are called "Max X" but they are actually not the maximum allowed size but the exact size at which the image appears. That means the dimensions of the displayed image will be distorted unless I manually calculate one of them from the other from the original dimensions of the image.
If I set the image stretch to anything but None, the image is sized so it fits the entire editor window. It should be visible only within the limits set by Max Width and Max Height, unless they are 0, but they are ignored.
Yes, MaxHeight/MaxWidth both property only affect non stretch mode. This is correct behavior. I'll add description message as 'Applies only if the image stretch property is None.'
Max Width and Max Height doesn't work correctly, and they certainly don't work together with the selected image stretch mode.