Hi José, there is a setting you can change (under "B" below).

(1) In a new tab, type or paste about:config in the address bar and press Enter/Return. Click the button accepting the risk.

(2) In the search box above the list, type or paste neww and pause while the list is filtered

(3) Review/Adjust the preferences as follows:

(A) browser.link.open_newwindow - for links in Firefox tabs

This is the one that has a checkbox on the Preferences page:

• 3 = divert new window to a new tab (default)
• 2 = allow link to open a new window
• 1 = force new window into same tab

(B) browser.link.open_newwindow.restriction - for links in Firefox tabs

By default, if a page sets width, height, or toolbars for a popup, Firefox will let it be a separate window. To force those into a tab as well, you can change this preference to 0:

• 0 = apply the setting under (A) to ALL new windows (even script windows with features) <= you might want to try this
• 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

(C) 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
• 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 if things go haywire, right-click each "modified" preference and choose Reset.

I have a test page here: https://www.jeffersonscher.com/res/popit.html

Any improvement?

Perfect!

browser.link.open_newwindow.restriction was set to 2....I changed it to "0" as per your guide, and it worked!

Thank you very much, jscher2000!

In addition, this is an excellent guide if I want to make other changes in the future: bookmarked and read-listed.

Cheers!