658667 - Status bar causes flicker with "popup" elements

Status: UNCONFIRMED

(Firefox :: Tabbed Browser, defect, P5)

Description

[shadow.bugzilla]

User-Agent:       Mozilla/5.0 (Windows NT 5.1; rv:2.0.1) Gecko/20100101 Firefox/4.0.1
Build Identifier: Mozilla/5.0 (Windows NT 5.1; rv:2.0.1) Gecko/20100101 Firefox/4.0.1

Here's the setup.  Say there is a <div> element on the page that has been absolutely positioned and its display set to none.  This element's display is toggled using JS in the onmouseover/out events of an <a> element.
When this <a> element is near the bottom of the viewing area, the popup will flicker when the <a> is hovered.  I found that it actually triggers the onmouseover event, then the onmouseout event, then the onmouseover again.  A friend and I determined that the status bar "widget" is causing it.  When the flicker occurs the status bar is on the right side of the screen, and on the left when the flicker does not occur.  The issue occurs with visibility instead of display, and the flicker also occurs using the :hover CSS psuedo class on an <a> element.

Reproducible: Always

Steps to Reproduce:
1. Build a normal webpage with some dummy content and an <a> tag at the bottom.
2. Set up a :hover CSS style or onmouseover/out JS event handlers.
3. Load the page in FF4 and scroll so that the link is just visible at the bottom and move the mouse over it.

Actual Results:  
In the case of JavaScript onmouseover/out, the onmouseover event is fired twice, which could lead to very unexpected results in certain applications.
In the case of CSS the popup simply flickers, which is just a minor nuisance.

Expected Results:  
No flickering.  Only one onmouseover should be fired.

An HTML test document will be attached.

Comment 1

[shadow.bugzilla]

Attachment: HTML test case document