301558 - DHTML menu not being redrawn correctly

Status: NEW

(Core :: Layout, defect)

Description

[John]

User-Agent:       Mozilla/5.0 (Windows; U; Windows NT 5.1; nl-NL; rv:1.7.8) Gecko/20050511 Firefox/1.0.4
Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.1; nl-NL; rv:1.7.8) Gecko/20050511 Firefox/1.0.4

When dynmically moving & hiding or showing several adjascent DIVs at once which
are all aligned to the bottom of their parent container, one or more are not
redrawn in the right place. Apparently happens only if their y-coordinate and/or
dimension is the same.

Reproducible: Always

Steps to Reproduce:
1. Go to the sample page at http://7arcos.lochtienk.be/firefoxbugs.htm
2. Move the mouse horizontally over the menus at the bottom

Actual Results:  
With the four leftmost menus, each time a menu is closed and the next one is
opened, the closed menu appears to stick to the top of the opened menu, although
the menu script has moved it correctly and it should be bottom-aligned with the
rest of the menus. 

Expected Results:  
The closed menu should be redrawn where it was when the page was first loaded,
just like it happens with the two righmost menus.

Apparently, when closing the menu and opening an adjascent one, the closed
menu's new x and y are not taken into account until the other menu is closed as
well.
Oddly enough, this only seems to happen if the two menus have the exact same
dimensions (i.e. same width and height), or if the old y-coordinate of the
closed menu matches the new y-coordinate of the opened menu.

A possible workaround is to make sure no two adjascent menus have the same
dimensions (one pixel difference is enough).

Comment 1

[Bob Clary [:bc] (inactive)]

John, I can see the same behavior in Deer Park (Firefox 1.1) on winxpsp2. It
appears that sometimes when the previous menu item is hidden, the underlying
content is not redrawn. From your description, this sounds like a layout bug,
but to get more traction the developers will need a testcase. Could you create a
minimal testcase by trimming your page to a minimum size to illustrate the
specific issue and attach it to this bug using "Create New Attachment"?

Comment 2

[José Jeria]

Could you please create a minimized testcase (as small as possible) and attach
it to this bug?

Comment 3

[John]

Attachment: Minimized testcase

Comment 4

[John]

Additional info: in creating the testcase, I noticed this behaviour disappears 
when the menu's parent div (which is absolutely aligned from the bottom of the 
window) doesn't have 'left' or 'right' in its style definition (i.e. when 
removing 'left:0px' or 'right:0px' from line 59 in the testcase).

Comment 5

[Guilherme Lima]

WFM