850982 - long firefox sessions with many tabs opened cause Firefox to cover the Windows Task Bar when it is set to Auto Hide

Status: UNCONFIRMED

(Core :: Widget: Win32, defect)

Description

[pork]

User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:22.0) Gecko/20130312 Firefox/22.0
Build ID: 20130312031046

Steps to reproduce:

Set windows taskbar to auto-hide
Open a firefox session
Browse opening many tabs (and/or windows) over an extended period of time (not sure how long yet)
attempt to mouse into the taskbar


Actual results:

Firefox covers the row of pixels that make up the "hidden" taskbar


Expected results:

The windows taskbar appears.

Comment 1

[Virgil Dicu [:virgil] [QA]]

Could you post a screenshot?

Mozilla/5.0 (Windows NT 6.1; WOW64; rv:22.0) Gecko/20130314 Firefox/22.0

This WFM at a first glance with Nightly. Could you post a screenshot/screencast?

Comment 2

[pork]

I have actually figured out what causes the issue. It's not due to long sessions, but seemingly related to flash video such as youtube. 

Open a flash video on a multimonitor setup and set it to fullscreen
Move the youtube window to a different display
Close the fullscreen video.
Attempt to mouse into the taskbar. It will not return. 

I have uploaded a video (ironically?) to YouTube to demonstrate, as a screenshot doesn't explain the issue well enough (IMO) 

www.youtube.com/watch?v=FoIjItyUl_4

Comment 3

[Virgil Dicu [:virgil] [QA]]

Hmm. I actually saw this the first time I tried (Nightly), but I can't reproduce anymore.
Used Win-Shift+ Arrow to move the youtube window to a different screen. 

Could you verify if this is actually specific to Firefox? Does IE behave the same?
Is it a regression? Did it previously work in previous Firefox versions?

Comment 4

[pork]

Bug does not present itself with IE.
Bug has been present for quite some time 

Bug is also present on the Aurora, Release, Beta, and Nightly UX. My guess this it is somehow related to using win-shift+arrow to move the windows between displays. 

It seems at first glance that for whatever reason, Firefox forgets that one display has the taskbar and it needs to resize itself accordingly when coming in from a display that doesn't.

Comment 5

[pork]

Bug can be reproduced without flash:

Start Fx on main display with hidden taskbar.
win-shift-arrow to a different display, toggle fullscreen (F11) on then off
Move back to main display and the bar is hidden. 
* Toggling F11 again on the main display will fix it and bring back the taskbar, but moving the window between displays again brings back the incorrect behavior. 

Seems to happen if anything at all was fullscreen during the session. ie. if you began the session, full screened a video on youtube, and went on your merry way for hours before moving the Fx window between displays, it will still happen.