1111091 - Tab bar jitters when tab curve width is less than 3px

Status: RESOLVED FIXED

(Firefox :: Theme, defect)

Description

[Brian Grinstead [:bgrins]]

See Bug 1096542.  After a lot of investigation, this happens in the following conditions:

* Tab curve width is less than 3px (the width of the tab separator elements)
* Customized tab bar to separate new tab button from tabs
* A tab is opened without the mouse being on the tab bar
* An overflow happens on the tab strip, and apparently the ::after element for the tab separators is being taken into account when ensureElementIsVisible is called.  This basically causes underflow/overflow to volley back and forth to each other.

STR for OSX:
Customize and put the tab button plus another button in the tab bar, separated from tabs
Resize window to 960px
Open 3 tabs
Open a 4th with a middle mouse click
Jittering on the tab strip ensues.  See Bug 1096542 for more test cases

Comment 1

[Brian Grinstead [:bgrins]]

Attachment: last-tab-separator-with-separated-new-tab-button.patch

This is one potential solution - we could just make sure that the splitter doesn't extend and increase the size of the tab.

Comment 2

[Brian Grinstead [:bgrins]]

The reason this is happening is that the extra width on the separator is causing the overflow to happen, which causes the ::after element to go away (since it isn't selected anymore)

Comment 3

[Matthew N. [:MattN]]

Comment on attachment 8535913 [details] [diff] [review]
last-tab-separator-with-separated-new-tab-button.patch

Review of attachment 8535913 [details] [diff] [review]:
-----------------------------------------------------------------

::: browser/themes/shared/tabs.inc.css
@@ +317,5 @@
>  }
>  
> +/* Handle a case where the last separator in a customized tab bar with a
> +   separated new tab button causes the width of the tab to extend and causes
> +   jittering with a small tab curve width (Bug 1100578). */

r=me with the corrected bug number. It's not ideal but the solution makes sense and it's straightforward.

Comment 4

[Brian Grinstead [:bgrins]]

Attachment: last-tab-separator-with-separated-new-tab-button.patch

Updated bug #

Comment 5

[Brian Grinstead [:bgrins]]

https://hg.mozilla.org/integration/fx-team/rev/94be697bd801

Comment 6

[Carsten Book [:Tomcat]]

https://hg.mozilla.org/mozilla-central/rev/94be697bd801