468838 - tab bar vibrates when browser.tabs.tabMinWidth set lower

Status: UNCONFIRMED

(Firefox :: Tabbed Browser, defect)

Description

[Oakwine]

User-Agent:       Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.5; en-US; rv:1.9.1b3pre) Gecko/20081209 Shiretoko/3.1b3pre
Build Identifier: Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.5; en-US; rv:1.9.1b3pre) Gecko/20081209 Shiretoko/3.1b3pre

I set my browser.tabs.tabMinWidth to 40.  When I open enough tabs to trigger the overflow scroll arrows on the tab bar, the browser constantly adds and removes the scroll arrows, causing a visual vibration in the tab bar.

Reproducible: Always

Steps to Reproduce:
1. Open the image attached to this report with an image browser.
2. Start Shiretoko with a new profile (It probably doesn't need a new profile, but I did it anyway to make sure).
3. In about:config, set browser.tabs.tabMinWidth to 40.
4. Close and restart Shiretoko to allow the tabMinWidth setting to activate.
5. Set the width of your browser to match the width shown in the image you opened in Step 1.
6. In the first tab, visit a website with lots of links (example: fark.com ).
7. Open 13 links from that page into new tabs by middle-clicking.
8. Click on the last tab to bring it into focus.
Actual Results:  
On my Mac, the tab bar begins to vibrate as Shiretoko can't decide whether to show or hide the scroll arrows on the tab bar. (It also happens with other combinations of browser width and number of tabs.)

Expected Results:  
The tab bar does not vibrate.

A Windows user was unable to reproduce the problem.

Comment 1

[Oakwine]

Attachment: An image to help set the browser width to trigger this bug

Comment 2

[Anders]

I have the same problem, I've had it since 4.0 beta 2 (didn't try earlier versions) and it still exist in the newest Minefield today.

I use the default tab width by the way, so the title of this bug is a bit limiting, it doesn't seem to have anything to do with tabMinWidth.

I made a animation of two screenshots to illustrate what it looks like. In the animation I've moved the tabs to the title bar with some CSS, but I've confirmed that the problem still exists with default userCSS as well.

I'm on Windows 7 x64 and Minefield nightlies.

Comment 3

[Anders]

Attachment: Illustration of the problem