53460 - Cellpadding destroys hover effect on table cells

Status: VERIFIED DUPLICATE of bug 5693

(Core :: Layout, defect, P3)

Description

[Sam Allen]

BuildID:    2000092005

When the hover pseudo-class is activated on a table cell that has cellpadding, 
a reflow is done even when one is not required, such as when only the 
background-color of the table cell changes. The cellpadding is removed, and the 
entire table shifts, potentially causing a performance degradation.

Reproducible: Always
Steps to Reproduce:
1. Open the attached testcase.
2. Mouse over the text "Here" in the left table cells for each part of the 
testcase.

Actual Results:  No reflows should have been triggered; only repaints should 
have occurred.			

Expected Results:  For the first part of the testcase (the part that uses 
cellpadding), reflows are consistantly triggered, resulting in a messy repaint 
and an unacceptable user experience. 

When testing this bug you will run into bug 48771, which means that it may be 
tricky to activate the hover psuedo-class.

Admittedly, the "performance degradation" demonstration part of the testcase is 
somewhat pathological, but any unneccessary reflow is actually a performance 
performance degradtion.

Comment 1

[Sam Allen]

Adding keywords.

I'm fairly certain this is a regression because I tested this stuff more than a 
year ago and it wasn't this bad.

Comment 2

[Sam Allen]

Attachment: the aforementioned testcase

Comment 3

[Heikki Toivonen (remove -bugzilla when emailing directly)]

joki changed the hover code a little while ago so it could be him, reassigning.

Comment 4

[Heikki Toivonen (remove -bugzilla when emailing directly)]

Setting 

pref("nglayout.events.showHierarchicalHover", false);

in all.js makes the problem go away, so I believe this is a duplicate of bug 
5693.

Comment 5

[Heikki Toivonen (remove -bugzilla when emailing directly)]

*** This bug has been marked as a duplicate of 5693 ***

Comment 6

[Stephen Walker]

vrfy dup