628267 - Tab and content rendering faulty when performing tab functions (close, open, switch)

Status: RESOLVED WORKSFORME

(Core :: Web Painting, defect)

Description

[a.barcomb]

User-Agent:       Mozilla/5.0 (Macintosh; Intel Mac OS X 10.6; rv:2.0b9) Gecko/20100101 Firefox/4.0b9
Build Identifier: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.6; rv:2.0b9) Gecko/20100101 Firefox/4.0b9

This problem developed after upgrading from b7 to b9; it is not known if it was present in b8.  

If a new tab is opened (using either apple-N or apple-click on a link), the entire content of the current tab will briefly vanish and then be re-drawn.  When the number of tabs exceeds those which can be displayed without scrolling, portions of the tab bar vanish and remain hidden for some time, and the content of the current tab vanishes for some time as well.  The attachment 'tabs_missing' demonstrates how the screen looks when I open a new tab.  The tab which is visible in the tab menu is not the current tab.  'actual_tabs' shows what the screen looked like before performing this function.  This particular problem happens every time.

When I switch from one tab to another tab, the new tab takes a very long time to render.  Often parts of the page render, and other parts do not, and it is necessary to switch back and forth between tabs in order to get the tab to render.  This happens when the tab in question has already completely loaded the page.  This problem occurs some but not all of the time, and seems to be more likely to happen when there are more tabs open (I observed it happening regularly after I had opened several tabs from my RSS feeds, and less frequently after most of those tabs were closed).  The screenshot 'switch_tab' demonstrates how it appears.  This particular page did not draw further on its own until I switched to another tab and back to this tab.

Finally, closing the current tab, causes the tab menu to disappear in a manner similar to that described with opening the new tab.  This happens every time when the number of tabs exceeds the number which can be shown without scrolling.  In addition, the content of the new active tab is not rendered (as in the tab switching) until I switch between the tabs.  The screenshot 'closed_tab' demonstrates this issue.  

Reproducible: Always

Steps to Reproduce:
1. Open a lot of tabs to ensure it happens every time
2. Try to open new tabs, close tabs, or switch between tabs
3.
Actual Results:  
Problems rendering tabs and tab content.

Expected Results:  
Normal rendering.

This may be related to bug 624118 but the problems are observed under additional circumstances (including when the number of tabs does not exceed the number which can fit without scrolling).

Tab preferences are set to: open new windows in a new tab (yes), always show the tab bar (yes), and switch to new tab immediately (no).  The following extensions are used: Adblock Plus 1.3.3, BetterPrivacy 1.43.3, Feedback 1.0.3, Ghostery 2.4.2, HTTPS-Everywhere 0.9.2, It's All Text! 1.5, NewsFox 1.0.6.2, and Stop Autoplay 1.2.

This problem has been observed on two different profiles with different themes.

Comment 1

[a.barcomb]

Attachment: tabs_missing

Comment 2

[a.barcomb]

Attachment: switch_tab

Comment 3

[a.barcomb]

Attachment: closed_tab

Comment 4

[a.barcomb]

Attachment: actual_tabs

Comment 5

[a.barcomb]

I forgot to mention that rendering issues also occur when one tab is moved to a new window.  The original window reacts in much the same way as it does when a new tab is opened.

Comment 6

[a.barcomb]

Bug is resolved by upgrading to Mozilla/5.0 (Macintosh; Intel Mac OS X 10.6; rv:2.0b10pre) Gecko/20110124 Firefox/4.0b10pre