-
about:config in the address bar and press Enter/Return. Click the button promising to be careful or accepting the risk.
-
In the search box: Type or paste "neww" to filter the list
-
Adjust the preferences as follows:
browser.link.open_newwindow - for links in Firefox tabs
3 = divert new window to a new tab (default)
2 = allow link to open a new window
1 = force new window into same tab <= Try this one
browser.link.open_newwindow.restriction - for links in Firefox tabs
0 = apply the setting under (A) to ALL new windows (even script windows) <= Try this one
2 = apply the setting under (A) to normal windows, but NOT to script windows with features (default)
1 = override the setting under (A) and always use new windows
browser.link.open_newwindow.override.external - for links in other programs
-1 = apply the setting under (A) to external links (default)
3 = open external links in a new tab in the last active window <= Try this one
2 = open external links in a new window
1 = open external links in the last active tab replacing the current page
To return to normal, right-click each modification and choose Reset.
Test page: https://jeffersonscher.com/res/popit.html