[cubefox]

Suggestion: When highlighting text, you want to use "multiply" blend mode (a.k.a. subtractive color mixing) instead of opacity. Opacity makes black text lighter/greyish, which is not how physical text markers work, or colored sheets of transparent plastic.

[m4rc1e]

Thanks for the suggestion. I plan on having user selectable blend modes. Currently, it's using the "difference" blend mode. This mode makes it easy to spot shifted images.

[m4rc1e]

I've just implemented user selectable blend modes. I've included the multiply mode as well. Thanks for your feedback.

[cubefox]

Cool!