This sounds a little bizarre, could you elaborate? Is there a page you're trying to open new tabs or windows from that's not working? Beyond running or not running, I'm not sure Firefox controls what Java does.

If you are expecting a popup window and not getting it, you may need to adjust the popup blocker settings or individual site permissions. Does this article help: Pop-up blocker settings, exceptions and troubleshooting?

If you are a developer and you want to increase your odds that window.open() launches a separate window rather than a new tab, you would need to add features. See:

• https://developer.mozilla.org/docs/Web/API/Window/open
• https://jeffersonscher.com/res/popit.html

The solution was to enable pop-up boxes. Many thanks.