Could you try adding the exception through the Permissions panel of the Page Info dialog. While you are on the page that is going to call window.open() and before you trigger it, you can call up the dialog using any of these:

• right-click a blank area of the page and choose View Page Info > Permissions
• (menu bar) Tools menu > Page Info > Permissions
• click the padlock or "i" icon to the left of the site address, then the ">" icon, then More Information > Permissions

Scroll down to "Open Pop-up Windows" and uncheck the "Use default" box, and then select the Allow permission.

There's no Save button in this dialog, it should be saved in real time as you make changes. However, I'm not sure everything is retained once your private session ends.

Hi Jscher,

I went to the page and it's already unticked. :S

Perhaps this is a new issue with using specific named windows. I assume using "_blank" doesn't cause this problem?

I think it is new - I was able to do this earlier this week and it was updated.. yesterday? or maybe the day before so might be new bug introduced then

I haven't tested _blank yet

Does it make a difference whether multi-process is enabled or disabled?

• browser.tabs.remote.autostart.2 = true/false

I tried changing the setting to no avail :(

Does it work if you allow all pop-ups?

yes, I've allowed pop-ups and added the domain / ips to allowed sites to no avail