What does your feature entail? What is it for? How will it affect existing workflows or user experience?
In Safari, if you right click on a tab header, and hold the option ⌥ key, the menu item "close tabs to the right" changes to "close tabs to the left", provided you are not selecting the leftmost tab. I think Orion should mimic this behaviour.
What are the exact ways that you see a user using your proposed feature? Please go into as much detail as possible, and provide examples of how other browsers/apps implement this feature, if applicable. If your feature suggestion adds on to an existing feature, how would it work into it to extend its usefulness?
I find this functionality extremely useful and it is probably the only thing I actually miss from Safari. It allows you to quickly arrange the tabs you want and close those you don't. Currently if I have two or more tabs next to each other and I want to the close the rest, I have to move every tab I want to save all the way to the left, and then close tabs to the right of them. For multiple tabs this is a pain. In Safari I can do this operation in at max two mouse clicks.