New tabs opened within container tab don't mantain current container in certain cases

[yphastos]

• Multi-Account Containers Version: 6.1.0
• Operating System + Version: MacOS X 10.13.6
• Firefox Version: Developer Edition, 69.0b14
• Other installed Add-ons + Version + Enabled/Disabled-Status:

Actual behavior

Case 1, opening a frame in a new tab/window:
When we have a container with a page with frames, right clicking in a frame, and choosing This Frame > Open Frame in New Tab(also in new Window), the frame does open in a different Tab/Window, but it DOES NOT maintain the container the original page was opened at.

Case 2, opening a new tab via Alt+Enter in the URL bar
Have any url in the address bar while in a Container Tab, and press alt+enter. The url opens in a new tab as expected, but it DOES NOT maintain the current container.

Both cases make that session/cookie dependent pages will not work because they (obviously) don't carry out them across containers.

Expected behavior

Opened frames/tabs/windows from within a container tab, should open in a tab of the same container.
The same should happen when opening a new tab via "alt+enter" in the url bar.

Steps to reproduce

Case 1:

1. Have a page in a container, which contains frames
2. Right click within a container and choose This Frame > Open Frame in New Tab (or new Window)
3. The page does open in a new tab, but NOT on the same container as the original one.

Case 2:

1. Have any page within a container.
2. have any url in the address bar, and press Alt+Enter.
3. The page does open in a new tab, but NOT on the same container as the original one.

Notes

Other cases DO maintain the current container, e.g.

Ctrl+click on any link
Middle click on any link
Right click on a link, and choose Open Link in New <current container> Tab

[patrick-webs]

" When we have a container with a page with frames, right clicking in a frame, and choosing This Frame > Open Frame in New Tab(also in new Window), the frame does open in a different Tab/Window, but it DOES NOT maintain the container the original page was opened at."

I am seeing this behavior on Firefox 69.0.1 release version now. This worked fine in 68 and before as I was regularly using the feature, but now my firefox seems to have updated and broke it.

[robsonsobral]

The ALT+ENTER issue is annoying!

[ivanperez-keera]

If you are in a container and press Ctrl+Tab, the new tab does not retain the container. It would be nice to have a key shortcut to open a new tab "in the same container", meaning, in the current one, regardless of which one that is (without having to remember the number for each container).

[jwbth]

For the last two comments, please see #480 and #462.