Clicking opens a new window; make it stop!

That depends on how the app is written. One of the few exceptions to allowing actual windows being open is a JS trigger with exact dimensions. If you want to forbid sites opening these, browser.link.open_newwindow.restriction = 0 would also turn these into new tabs.

Hi JBR!

I did previously try that and it still does not work. I appreciate the response and will keep trying.

Have a great day!

In an accounting/payroll software application, a new window opens instead of a new tab. How to I fix this? I've already tried about:config method as well as the simple 'tabs and browsing' method within Firefox settings. Nothing seems to work.

You'd need to liaise with your software vendor then, in case there's no publicly accessible example of the analogous code to inspect how they're achieving that.