EDIT: It seems like websites that prompt for a username/password GUI dialog box seem to work correctly. However, if I try to open a duplicate tab, the feature breaks again. Looks like the problem may be related to Window focus.

I'm just curious if this feature work correctly for other people. If so, I guess I'll have to figure out which Firefox extension is causing this odd behavior.

Mozilla doesn't develop or support waterfox, and so you won't find much help at this site for it. You can download an official build of Firefox from www.getfirefox.com, which is supported, and we can help you with any problems with that.

Waterfox often has issues that are not in official Firefox and so we can't and don't support it.

Start Firefox in Safe Mode to check if one of the extensions (Firefox/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem.

• Switch to the DEFAULT theme: Firefox/Tools > Add-ons > Appearance
• Do NOT click the Reset button on the Safe Mode start window

• https://support.mozilla.org/kb/Safe+Mode
• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes