I’d like to create context menu items for various links within a site but each time you jump to a link I want the page loaded in a tab so that the loading delay of each of these links is only experienced once. Basically, think of a site where I have 10 tabs open to various pages on that site - I’d prefer to have 1 tab but a context menu of “pages/tabs” that I can then select. Each page isn’t reloaded, which resets page state, instead it just shows that page just like switching tabs.
If your add-on is a WebExtension, then no, you can’t.
Otherwise you can get the XUL-Element that represents the tab in the tab bar (how this works depends on the context you are in) and set its hidden attribute.
If you have a SDK-add-on, something like this should work: