Crop tool straighten guide lines need some more weight and contrast#389

On a Mac, they are too light to be seen on top of the image. I find it easiest to align to verticals as perspective doesn’t make those at camera level catywumpus. Sometimes lines need to be light, other times dark to have contrast with the image. I don’t suggest XORing them in as the result might be confusing. Just a bit more beef and some choice.