625715 - Private browsing affects all browser instances

Status: RESOLVED DUPLICATE of bug 463027

(Firefox :: Private Browsing, defect)

Description

[P.L.]

User-Agent:       Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.2.13) Gecko/20101203 Firefox/3.6.13
Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.2.13) Gecko/20101203 Firefox/3.6.13

Scenario:

- I had one browser instance open with around dozen tabs containing various work-related data in Flash applications.
- I opened another browser instance and started private browsing in that instance so the work data in the Flash applications in browser instance 1 would be safe.

End result:

- Entering private browsing in browser instance 2 closed the other one so I was left with just one browser instance, in private browsing mode.

Comments:

This is exactly the thing I was trying to avoid as it, effectively, wiped clean hours of work done in the tabs containing Flash, in browser instance 1.

This is either a bug in private browsing or a bug (omission) in Firefox documentation as neither Firefox help nor various searches done in Google said anything about private browsing closing all other browser instances (or am I just blind?) without question (I've used private browsing before but only with one browser instance open at a time).


Reproducible: Always

Steps to Reproduce:
1. Open browser instance 1
2. Open browser instance 2
3. Enter private browsing mode in browser instance 2
Actual Results:  
Only one browser instance is left, with all other instances being closed.

Expected Results:  
1. Browser instance 1 remains as it was
2. Browser instance 2 enters private browsing mode

Typically, I would rate this as a normal severity bug but since it made me lose hours worth of work, I'm rating it as critical (severity description says "causes you to lose data", which it did, even if the lost data was in Flash applications).

Note: I do not wish to emphasize Flash in this context, it was simply unexpected (for me) that all other browser instances were closed when entering private browsing mode in one instance since this was not mentioned anywhere (or I've developed acute dyslexia) in the searches I made.

Comment 1

[Jo Hermans]

Yes, it's application wide. But there's no such thing as a "browser instance". They're just windows in the same application (unlike Internet Exploder).

Comment 2

[lt.billy]

I noticed the same issue.
Understanding that they are windows in the same application, is there a way to make it possible to have private and non private windows open at the same time. 
That seems like that ideal way to handle the situation. Maybe it isn't a bug, but an improvement can be made.