222198 - slow scrolling when fixed elements are partially outside the viewing area

Status: RESOLVED WORKSFORME

(Core :: Web Painting, defect)

Description

[John McCormick]

User-Agent:       Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.6a) Gecko/20030929 Firebird/0.7+
Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.6a) Gecko/20030929 Firebird/0.7+

When a page contains:
1. elements with a style of position: fixed;
2. any of those elements are partially outside the viewing area (window is too
small, element too large, etc)

Two things happen:
1. Scrolling is slowed drastically. 
2. Painting problems may occur (see bug 186696, bug 183495).

This is a separate problem from general slowness resulting from fixed elements
(bug 201307). See the attached test case.

Reproducible: Always

Steps to Reproduce:

Comment 1

[John McCormick]

Attachment: demonstrates slow and fast scrolling

This is Chu Alan's test case from bug 201307, from whence this bug came.

Comment 2

[John McCormick]

Just downloaded Mozilla 1.5, Firebird 0.7, and I'm happy to say that this
slowdown doesn't occur in these!

It's wierd how this problem keeps coming and going though. Resolve WFM, reopen
if it comes back, I guess...?

Comment 3

[David E. Ross]

This might be a symptom of bug 124150.  See my comment 66 in that bug.  

Comment 4

[John McCormick]

Worked in 2003, still works in 2008, resolving.