1191743 - (Win7) Alt+Tab panel disappears when firefox is in fullscreen mode (under certain conditions)

Status: NEW

(Firefox :: General, defect)

Description

[arni2033]

STR:   (tested on current Nightly 42; the bug is presented for a very long time)
1.   Open Firefox window, press F11 to switch to fullscreen mode
2.   Press Alt (don't release)
3.   Press and release Tab [panel with opened windows will appear]
4.A) Press Escape          [panel will be hidden]
4.B) Click on content area [panel will be hidden]
5.   Press and release Tab
(!)Make sure that there's as short as possible delay between Step 4 and Step 5: less than 1 second

RESULT:
After Step 5 the popup with opened windows will appeared BUT after 1-2 seconds it disappeared.

EXPECTATIONS:
It should stay visible. Note that if you wait "second or two" after Step 3, then you will still see that popup: this is expected behavior.

Comment 1

[arni2033]

Xidorn, is this a known issue? 1210452 is a dupe with additional series of steps-to-reproduce. I don't know if component should be "Core- Widget: Win32 /Shell integration" and if you're right person to ask
One thing is clear: it's long-standing and is not a result of recent work.

Comment 2

[Xidorn Quan [:xidorn] UTC+11]

I cannot reproduce either this or bug 1210452 on Windows 10, so it's probably a Windows bug which has been fixed in later systems. I don't have idea how a window can hide itself from that panel. And I currently do not have Windows 7 environment on hand.

Could you reproduce this issue with other fullscreen applications e.g. IE?

jimm, any idea how this could happen and how can we fix this?

Comment 3

[arni2033]

IE and GoogleChrome work fine with STR in this bug. But, after Step 5 they show Windows taskbar in addition to panel with opened windows. Maybe this is some hack used by both of them.

Comment 4

[Jim Mathies [:jimm]]

(In reply to arni2033 from comment #0)
> STR:   (tested on current Nightly 42; the bug is presented for a very long
> time)
> 1.   Open Firefox window, press F11 to switch to fullscreen mode
> 2.   Press Alt (don't release)
> 3.   Press and release Tab [panel with opened windows will appear]
> 4.A) Press Escape          [panel will be hidden]
> 4.B) Click on content area [panel will be hidden]
> 5.   Press and release Tab
> (!)Make sure that there's as short as possible delay between Step 4 and Step
> 5: less than 1 second


I can't reproduce this on windows 7. With both 4a and 4b the Windows switch panel closes and firefox regains foreground status. Are we missing an important step to reproduce here? I also don't understand step 5. If you go into fullscreen on this bugzilla bug page, and hit tab after either 4a or 4b, tab will move focus around the page.

Comment 5

[arni2033]

(In reply to Jim Mathies [:jimm] from comment #4)
> tab will move focus around the page.
Nope. I don't release Alt after Step 2, so in Step 5 it works as Alt+Tab and shows the panel.

Comment 6

[arni2033]

And also Step 1 must have been more specific:
> 1.   Open Firefox window *in maximized mode*, press F11 to switch to fullscreen mode
If in Step 1 I open window *in normal mode*, then after Step 5 I get the same result as on Chrome/IE

Yes, maybe it's Windows' bug, which allows applications to take away the focus from Alt+Tab panel (and therefore hide it). But anyway, firefox shouldn't do that.

Comment 7

[Jim Mathies [:jimm]]

Still no luck.

Comment 8

[arni2033]

Maybe you have something installed/enabled which cancels Alt key if you Alt+Click. Well, that doesn't matter since I provided only the easiest scenario. There is a series of steps with the same result

1.   Open firefox window in maximized mode, press F11 to switch to fullscreen mode
2.   Press Alt+Tab to switch to another non-firefox non-fullscreen window, release both Alt and Tab
3.   Press Alt+Tab to switch to firefox window from Step 1, release both Alt and Tab
    [DON'T make any pause between Step 3 and Step 4]
4.   Press Alt+Tab to open Alt-tab panel, release Tab, DON'T release Alt

Result: If you really made no pause between Step 3 and Step 4 - Alt-tab panel disappears.

I also bisected this - the bug was introduced between 2011-09-01 and 2011-09-02
(the same time I started using Firefox!!). Before that, firefox behaved like other applications.
http://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=d772dfb96ba1&tochange=0664108eb19d
I think it's bug 617052.

Comment 9

[arni2033]

Note: I've disabled the Windows mechanism "show tab which is selected in alt-tab panel" long time ago

Comment 10

[arni2033]

Bonus:  If I keep pressing Alt+Tab ~0.5s after Alt-Tab panel disappears,
        it keeps disappearing again and again.

NI if you need additional information from my side.

Comment 12

[Sylvestre Ledru [:Sylvestre]]

Not blocking the release as we shipped several already with this bug and it didn't cause too much noise.