(In reply to Kazumasa Hasegawa (Kazz) from comment #7)
Why adding the same functionality to the context menu?
Because users expect it there, as other browsers have it. We've had repeated requests, e.g. bug 1382929 and its dupes, etc.
The functionality is also not entirely identical to left-clicking the new tab button - the new tab will use the same container as a tab you click on, and open immediately to the right of that tab. The new tab button just opens tabs at the end. You can middle click it to get the same behaviour as the context menu, but that's less discoverable. The context menu's behaviour is similar to the behaviour of the same menuitem in other browsers (ie opens immediately to the right of where you click).\
(In reply to Kazumasa Hasegawa (Kazz) from comment #4)
- The labels of other menu items are basically "do something + tab" like "Reload Tab" "Close Tab" and so on, but the label "New Tab" is not consistent with them.
But it's not really much like those other items - they act directly on the tab on which you click, and this one doesn't. Even if we switched to a verb ("Open Tab"), that would itself be somewhat confusing, because "Close Tab" closes the tab you click on, and the tab is already open, so having an item to "open" it would be confusing. So having the same formula everywhere but having it do something that is really pretty different from the other items would also not be great. This is also why there's a separator immediately after it.