642507 - Off-by-one error for browser.sessionhistory.max_entries in about:config introduced by Firefox 4.0 RC.

Status: NEW

(Core :: DOM: Navigation, defect)

Description

[asandari]

User-Agent:       Mozilla/5.0 (Windows NT 6.0; rv:2.0) Gecko/20100101 Firefox/4.0
Build Identifier: Mozilla/5.0 (Windows NT 6.0; rv:2.0) Gecko/20100101 Firefox/4.0

In my Firefox 3.6 settings, I had set browser.sessionhistory.max_entries to 1. When I upgraded to the Firefox 4.0 RC I was no longer able to go back a page.

Reproducible: Always

Steps to Reproduce:
1. Set browser.sessionhistory.max_entries to 1 in about:config
2. Google an inane term and click on a link.
3. Hit backspace or the back button; note that you cannot go back.
4. Set browser.sessionhistory.max_entries to 2 in about:config
5. Repeat step 2 and click on another link within the website.
6. Hit backspace or the back button twice; note that you can only go back one page. 
Actual Results:  
In steps 3 and 6, you can only go back 0 and 1 times respectively.

Expected Results:  
In steps 3 and 6, you should be able to go back 1 and 2 times respectively.

Comment 1

[Boris Zbarsky [:bzbarsky]]

Olli?

Comment 2

[Olli Pettay [:smaug][[e-mail]]]

I'll look at this.

Comment 3

[:aceman]

Can confirm with Aurora 6 on Linux.