This extension is absolutely invaluable. It helps me figure out so many elements on a screen as I design websites.

Perfeito. Facilita demais o meu trabalho.

Good. it definitely does what it proposes. But it should have a percentage option. Percentage relative to the window in width and height.

Mas que buena. Muy útil sobre todo para desarrolladores y diseñadores que quieren sacar medidas en la pantalla.

De uso muy fácil. ¡¡¡100% recomendada!!!

Installed in Mozilla and Chrome, now works correctly on a site outside Mozilla, which I havent tried before. Sorry

Works as expected. Useful. I did not notice any performance degradation. Thanks.

excellent