@SantaOrlando I'm sure 8've said this before, probably in the oldest thread on the topic, but this was one of my favorite (and almost trivial to do) customization I had in old Opera. I changed the shortcut assigned to Button4 (the Back button on Navigator mice) to Back ! Close tab and if Back failed it would instead close the tab. Might be possible with javascript - not certain if code execution continues if history,back fails.