703971 - Firefox draws an added 1px white line at the bottom of a maximized window in Aero-enabled Windows with the taskbar located on the right/left/top and set to 'auto-hide'.

Status: RESOLVED DUPLICATE of bug 642851

(Firefox :: Shell Integration, defect)

Description

[WApp Kido]

Attachment: The screenshot of the white line artifact (seen against dark surroundings).

A horizontal one-pixel-high line of white color is layered over all graphics in a maximized Firefox window (over the Add-on bar too, if it is present) and is stretching all the way from the left edge of the window to the right one, going even over (or under) the scroll bar. The bug has been seen on two computers, one with some add-ons installed (Windows 7 x64) and another one with a perfectly fresh Firefox 8.0 installation without any extensions or themes installed (Windows 7 x86).

[Computer 1] User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:8.0) Gecko/20100101 Firefox/8.0
[Computer 2] User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:8.0) Gecko/20100101 Firefox/8.0

Reproducible: Always.

Steps to Reproduce:
1. Close all Firefox windows (i.e. exit Firefox).
2. Make sure that Windows Aero is turned on.
3. Go the the properties of the taskbar. Tick the "Auto-hide the taskbar" checkbox, select "Right", "Left", or "Top" in the drop-down list of the "Taskbar location on screen" combo box, and click the "Ok" button.
4. Open a Firefox window in maximized mode.

The bug is most noticeable against non-white and dark areas of web pages.

Expected Results: no artificial graphics should be added to the intended appearance of a web page, regardless of the mode of a Firefox window is opened in, the OS Firefox is running on, or the desktop configuration of the OS.

Comment 1

[HK]

It occured also in my environment.

*WindowsXP 32bit
*Firefox9 or 10
*"Visual Style" is turned on
*Firefox window is maximized
*Taskbar location is "bottom"

Comment 2

[tvkanters]

This bug still exists and shows up on external monitors.
As additional details: It appears not always to be a white line, but rather a line that is not being repainted properly. When toggling fullscreen mode on and off with F11, the 1px line will be as it was in fullscreen mode, even when switching tabs.

Comment 3

[etc]

This same issue also seems to kill steam notifications. They just plain don't appear when I'm maximized with the taskbar on my secondary display.

Comment 4

[Tim Abraldes [:TimAbraldes] [:tabraldes]]

Attachment: Concept patch

I stumbled across this code while looking into bug 758280.  I think something like the attached patch might fix this issue.  I'll test locally and continue looking into it.

Comment 5

[tvkanters]

Much thanks for giving the issue some attention.
I gave the diff a look, and while I'm not too familiar with C++ and might have read things wrong, it appears that you've added a check to make sure the that the white line is only placed when the taskbar is at the bottom. This could fix the issue on the primary monitor, but would still leave a white line on external monitors which (by default) don't have a taskbar.
Would it be possible to include a check to see if the screen that the Firefox window is maximised is in has a taskbar or is on a secondary monitor?

Comment 6

[Tim Abraldes [:TimAbraldes] [:tabraldes]]

Attachment: Concept patch v2

The attached patch also checks that Firefox in on the primary monitor.

Untested; not even sure this compiles, but I'll test it soon.

Comment 7

[Tim Abraldes [:TimAbraldes] [:tabraldes]]

Did some local testing.  With this patch applied, Fx doesn't display the line when the taskbar is set to auto-hide on the left, right, or top of the primary monitor.  However, the locally-built Fx failed to let the auto-hide taskbar appear when it was on the left, right, or top of the monitor.  To allow the auto-hide taskbar to appear, our window must not cover the entire monitor [1].  Since Nightly is leaving a 1-pixel line at the bottom of the screen, I think this is what is allowing the auto-hide taskbar to work correctly.  The right thing to do is probably to have the 1-pixel line exist on whichever side the taskbar is on.

I don't currently have a secondary monitor (not yet hooked up since I've been moving) so I haven't yet tested that situation.

[1] http://support.microsoft.com/kb/q179363

Comment 8

[tvkanters]

Cheers for the effort. If you'd like me to test a nightly, let me know.

Comment 9

[Tim Abraldes [:TimAbraldes] [:tabraldes]]

Preferring older bug