Open Bug 874282 Opened 7 years ago Updated 1 year ago

Firefox covers an auto-hiding windows taskbar when moved to the main display using SHIFT WIN


(Core :: Widget: Win32, defect, P3)

24 Branch
Windows 7




(Reporter: rjward0, Unassigned)


(Keywords: multi-monitors, Whiteboard: tpi:+)

User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:24.0) Gecko/20130519 Firefox/24.0 (Nightly/Aurora)
Build ID: 20130519031035

Steps to reproduce:

Set the Windows Task Bar to auto hide
Start firefox
Move firefox to a secondary display
using SHIFT-WIN, move Firefox to the main display

Actual results:

Firefox in its maximized state covers the area where the Windows Task Bar would normally be retrievable 

Expected results:

Firefox should not cover the windows taskbar
Same behavior with FF21 or a previous version?
Flags: needinfo?(rjward0)
Yes, just tested with 20.0.1, updated to 21.0 and tested again, happens on both.
Flags: needinfo?(rjward0)
Component: Untriaged → Widget: Win32
Product: Firefox → Core
This only seems to occur when HKEY_CURRENT_USER\Control Panel\Desktop\WindowMetrics\PaddedBorderWidth is set to 0 or smaller.

Hope this helps.
Related or duplicate of bug 467962 maybe?
This is just a guess but I'm thinking that when you move Fx to the main display, it positions itself right on top of the taskbar. Normally, this area is buffered by the (default) 4px border, but when there is a 0px border (still a border though :|) fx puts the tab content on top of the taskbar, covering it.

Makes sense to me, but I wont pretend it's based on anything more than speculation.
This issue persists on Windows 8 (0px window borders)
I'd like to amend the steps to repro: 

0.Set Windows Taskbar to autohide
1.Set PaddedBorderWidth to 0 or -1 
2.Start Firefox on your main display. 
3.If it isn't, maximize the Firefox window.
4.Using SHIFT-WIN, move the Firefox window to a secondary display the same resolution as the main display. If using windows 8 or higher, disable the taskbar on the second monitor. 
5.Using SHIFT-WIN, move the Firefox window (still maximized) back to the main display. 
6.Click on anything outside of the Firefox Window (including alt-tab)
7.Click the Firefox Window to bring it back into focus
8.Try to call the taskbar from the bottom of the main display.

Expected Results: The Windows Taskbar should rise from its hidden state, over the Firefox window.

Actual Results: The Firefox window is overlaid over the taskbar, preventing you from calling it.
Confirmed on Win7 with FF29 and 32. Tried various other apps and they don't exhibit this issue.

Gavin can you help route this to the right team?
Ever confirmed: true
Flags: needinfo?(
Not having looked into it deeply, someone on Robert's team might be able to help.
Flags: needinfo?(
I'll see if I can take a look this week
Assignee: nobody → tabraldes
I've been unable to repro this on my machine using the following steps:

 - Set Windows Taskbar to autohide
 - Set main monitor and extended monitor to same resolution
 - Set Taskbar to not show on extended monitor
 - Set PaddedBorderWidth to 0 or -1 (tried both)
 - Sometimes tried with Firefox already launched, sometimes tried launching Firefox after changing the above settings

  0. Maximized Firefox on main monitor
  1. Moved Firefox window to secondary display (tried using Shift+Win+arrow, mouse, and Win+arrow)
  2. Moved Firefox window back to main display (tried using Shift+Win+arrow, mouse, and Win+arrow)
  3. Unfocused Firefox (tried by alt+tabbing, clicking on things in other display, and clicking things in taskbar)
  4. Sometimes clicked around in other app
  5. Re-focused Firefox (sometimes by alt-tabbing, sometimes by clicking on Firefox window)
  6. Moved mouse to bottom of main display to bring up taskbar

I'm running the latest Windows 8.1 Pro on a Lenovo Ideapad Yoga 13 using the current release Firefox (29.0.1). Maybe this is easier to repro on Win7?
You may need to restart for changes to PaddedBorderWidth to take effect on new windows. Issue has persisted into Win 8.1u1 for me
Assignee: tabraldes → nobody
I have this problem on a laptop with Windows 10, upraded from 8.1.
I never did any fancy reconfiguration of the windows or desktop.
Just an autohiding task bar.  It is annoying because now I'm forced
to excute an Alt-Tab every time I need to access the task bar.

Does the status NEW mean that this problem is not confirmed yet?
(In reply to Toon van der Pas from comment #13)
> Does the status NEW mean that this problem is not confirmed yet?
It means that it is confirmed
My previous comment was based on experiences with FF up to version 40.0.3
A moment ago I updated FF to version 41.0 and very much to my surprise
the problem is gone!  FF no longer overlaps the emerging hidden task bar!

I'm happy.
Robert, could you confirm on your side it's fixed with FF41?
Flags: needinfo?(rjward0)
Unfortunately, I'm using FF41.0.2, on Win 8.1 and I still see the problem as described.
Hi! Sorry I've been unable to respond for so long. Issue has not been resolved in the latest nightly as of 2015-12-17
Flags: needinfo?(rjward0)
Priority: -- → P2
Whiteboard: tpi:+
Keywords: multi-monitors
Priority: P2 → P3
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