Firefox keep developer tools open after popup window closes

Question

A site has a popup window where you can send a message to someone. After the message is sent, the popup window closes. I'd like to see the requests made in the Firefox Developer window, but it closes when the popup closes. Is there a way to either keep the popup open or to keep the Dev tools open? This question is similar to this question about Chrome dev tools.

Answer 1

The accepted answer did not work for me, it kept closing anyway. However what did work was the solution presented here.

This involves using about:config to set the following values:

browser.link.open_newwindow                      1
browser.link.open_newwindow.restriction          0
browser.link.open_newwindow.override.external    3

After this, the popup will open in the same window. Then, the script cannot close the window since it is not the creator.