Strange "switch to tab" popup in FF39/40

[Yuri D'Elia]

Hi everyone. I have a strange issue with recent Firefox versions.

Since I've updated to FF39 and then 40 (actually, I'm running iceweasel
on linux), when typing stuff in websites that perform live suggestions
such as google.com, sometimes a menu popup appears in the top-left
corner listing the available "tabs" (the buffer list for the current
window) and with the text underneath saying "Switch to tab".

As if FF didn't recognize the current buffer/tab is active.

It's incredibly annoying. The popup often covers exactly the spot where
I'm typing. Switching buffers doesn't solve the problem. I have to close
the window or open a new one.

Generally speaking, I do _not_ want this notification feature. I
couldn't care less about background tabs, and it looks as something that
will be easily abused in the future. It also seems to trigger when
websites change their document title.

I couldn't find any relevant setting to disable it, or any documentation
about it whatsoever.

Did anybody else experience this issue?
I'm using the nightly build of pentadactyl.

Thanks.

[Yuri D'Elia]

On 19/08/15 18:03, Yuri D'Elia wrote:
> I couldn't find any relevant setting to disable it, or any documentation
> about it whatsoever.

Just to clarify, I searched in MDN/about:config about potential flags
related to tabs/notifications/etc but nothing came up mentioning this.

[Yuri D'Elia]

On 19/08/15 18:03, Yuri D'Elia wrote:

> Hi everyone. I have a strange issue with recent Firefox versions.
>
> Since I've updated to FF39 and then 40 (actually, I'm running iceweasel
> on linux), when typing stuff in websites that perform live suggestions
> such as google.com, sometimes a menu popup appears in the top-left
> corner listing the available "tabs" (the buffer list for the current
> window) and with the text underneath saying "Switch to tab".
>
> As if FF didn't recognize the current buffer/tab is active.

With luck (I found one site that triggered this effect consistently), I
was able to see that this popup is actually the url bar dropdown [it's
so long I didn't see it, I couldn't even recognize it].

It's a nasty side-effect of a work-around I'm using to let
uBlock/uMatrix work in the add-on bar, using the following rule:

style -name ublock * #nav-bar * { visibility: visible; }

In the latest FF versions, setting the children of #nav-bar to visible,
despite not showing the nav-bar, causes the urlbar to get focus in some
odd circumstance even if it doesn't receive any input.

As a work-around for the work-around, disabling the urlbar as well:

javascript gURLBar.disabled = true

seems to prevent the urlbar to get focus.

Although the ublock/umatrix popup issue seems caused by some issue in FF
itself, I have the impression that none of the projects have interest in
fixing the issue.

Is there a way I can hook to the "guioptions" variable, so that I can
add/remove the workaround as needed?