Bug 91202 – Fixed position elements not re-rendering when their position changes.

• Component: CSS
• Status: UNCONFIRMED

[Michael Johansen]

Created attachment 152180 [details]
List on the left, table footer on the right.

_Hope_ I'm filing this the right place.

There's appears to a bug in CSS3 handling in WebKit (bug is consistent in both Chrome and Safari, latest versions as of july 2012).

Bug: Elements with fixed position are not re-rendered immediately when other elements (which the fixed position elements' position rely on) are moved (in this case animated).

To better understand, see the screenshot: The list on the left is animated to slide left and right with jQuery (1.7.1), the table footer on the right has a fixed position to always be shown at the bottom of the table. However when the list on the left slides in (with the table following nicely), the fixed position table footer stays put. The footer only re-renders at the correct position if it is changed in some way; like when I'm manipulating the CSS of the footers DOM element or when I'm scrolling to the bottom of the page and the box-shadow is removed. Then the footer jumps left to it's new position, correctly rendered.

As a developer, it appears to me as an optimization bug, something along the lines of "since this element has fixed position we don't need to re-render it."

[Alexey Proskuryakov]

Do you have a test case that you could attach to the bug?

[Michael Johansen]

Created attachment 152726 [details]
A greatly stripped version of the frontend with the webkit bug, stripped as far down as I can without refactoring and without my boss asking me to do something else.