I guess the CTRL+K does not work when cursor is in any entry/input box. Is that correct? 

As for the new tab - when it's opened I have the cursor in URL bar and CTRL+K has no effect then. If I just press TAB to get out of the URL bar (web page gets focus) the CTRL+K works again.

The same happens here in bugzilla - when cursor is in bug number field, CTRL+K does not work.

You're correct Martin, I had not noticed that it is always related to the focus
being in an entry input/box. Once the focus is out of an input box, Ctrl-K works
again

Clarification: works from HTML textareas but not from HTML inputs.

Ctrl-L works. Did some experimenting using the Menu Wizard extension to switch the keybindings for Ctrl-L and Ctrl-K ... the results indicate that the problem is specific to the Ctrl-K key combination as opposed to specific to focusing the search box.

Looks like Ctrl-K performes the ancient input function of Killing the remainder of the input line to the right of the cursor.  I think I can count on 2 hands the number of times over the last few decades I've intentionally used Ctrl-K for killing the rest of the line, I can't count how many times I used Ctrl-K to navigate to Firefox's search box in the last week, so my vote is to revert the Firefox URL input bar to un-map or override the input rule of Ctrl-K to retain the previous behavior of navigation to the search box.

I suppose I could get used to a new keyboard shortcut for navigation to the search box, but if that's the case, I certainly hope it's the same across platforms - the Ctrl-# (Windows) vs Alt-# (Fedora) for switching tabs is already enough of a headache.

Yes, we need to disable the CTRL+K nonsense. Guys, how we can disable it for all Firefox GtkEntry elements? Thanks!

Introduced by this change:
https://git.gnome.org/browse/gtk+/commit/?id=423868b408e0997af9e9af6a3ae5bb1ff50a0965

(In reply to Martin Stransky from comment #6)
> Yes, we need to disable the CTRL+K nonsense. Guys, how we can disable it for
> all Firefox GtkEntry elements? Thanks!

One persons nonsense is another persons feature request...

Here is a css snipplet that disables the key binding:

@binding-set firefox
{
  unbind "<ctrl>k";
}

GtkEntry {
  gtk-key-bindings: firefox;
}

*** Bug 1215294 has been marked as a duplicate of this bug. ***

(In reply to Matthias Clasen from comment #8)
> (In reply to Martin Stransky from comment #6)
> > Yes, we need to disable the CTRL+K nonsense. Guys, how we can disable it for
> > all Firefox GtkEntry elements? Thanks!
> 
> One persons nonsense is another persons feature request...

Sorry, I don't mean to offend anyone.

> Here is a css snipplet that disables the key binding:
> 
> @binding-set firefox
> {
>   unbind "<ctrl>k";
> }
> 
> GtkEntry {
>   gtk-key-bindings: firefox;
> }

How we can pass that to the GtkEntry elements?

(In reply to Matthias Clasen from comment #8)
> (In reply to Martin Stransky from comment #6)
> > Yes, we need to disable the CTRL+K nonsense. Guys, how we can disable it for
> > all Firefox GtkEntry elements? Thanks!
> 
> One persons nonsense is another persons feature request...
> 
> Here is a css snipplet that disables the key binding:
> 
> @binding-set firefox
> {
>   unbind "<ctrl>k";
> }
> 
> GtkEntry {
>   gtk-key-bindings: firefox;
> }

How can I apply this CSS as a workaround?

You should be able to put this snipplet in $HOME/.config/gtk-3.0/gtk.css, but then it will apply to all entries in all applications.

Thanks a lot Matthias, workaround works fine ;)

What other options do the firefox maintainers have to ship this workaround
for every user (short of creating a css in each users homedir, which would
be undesirable for a number of reasons)? Subclass GtkEntry and call somewheregtk_binding_entry_remove(), a specially placed .css file that only 
applies to firefox?

Yes, we need to disable it in Firefox only but for all users - to restore the CTRL+K functionality. Is there any way?

This is driving me crazy since moving to Fedora 22.

Can someone provide the specific steps to re-enable ctrl-k to work properly in Firefox? It's worked this way for years (and still does on other platforms). 

Apologies if I'm piling onto the wrong bug.. this was the only one I could find.

John,

this is the current workaround:
more ~/.config/gtk-3.0/gtk.css 
@binding-set firefox
{
          unbind "<ctrl>k";
}

GtkEntry {
          gtk-key-bindings: firefox;
}

(In reply to Michele Baldessari from comment #16)
> John,
> 
> this is the current workaround:
> more ~/.config/gtk-3.0/gtk.css 
> @binding-set firefox
> {
>           unbind "<ctrl>k";
> }
> 
> GtkEntry {
>           gtk-key-bindings: firefox;
> }

THANK YOU!

(In reply to John Poelstra from comment #15)
> This is driving me crazy since moving to Fedora 22.

As another workaround, Ctrl+J works as well, and it's not that far away from Ctrl+K :-)

https://support.mozilla.org/en-US/kb/keyboard-shortcuts-perform-firefox-tasks-quickly#w_search

*** Bug 1234743 has been marked as a duplicate of this bug. ***

Upstream bug: https://bugzilla.mozilla.org/show_bug.cgi?id=1176929

(In reply to Kamil Páral from comment #18)
> 
> As another workaround, Ctrl+J works as well, and it's not that far away from
> Ctrl+K :-)

True, but Ctrl+J shows downloads in Thunderbird and Chrome, while Ctrl+K moves the cursor to a search box.  As a workaround, Ctrl+J is inconsistent with similar applications, and tends to be confusing.

Related Gtk+3 upstream bug report:
https://bugzilla.gnome.org/show_bug.cgi?id=749944

This is a regression introduced last September in Gtk+3, see here:
https://bugzilla.mozilla.org/show_bug.cgi?id=1176929#c40

The workaround in comment 16 didn't work for me, possibly because the keybindings are hardcoded and not defined in a .css file?

BTW. This bug is blocking official Mozilla switch to Gtk3 now:

https://bugzilla.mozilla.org/show_bug.cgi?id=1176929 (and many other dupes)

We make sure Gtk3 migration is as hard as possible. Good work guys!

This was fixed for 3.18.0 in f23. Time to retire this bug before it accumulates more acerbic comments.