Storytime: How I Lost and Found My Shift+F3

In August 2007, some X users wanted the function keys (F1 - F12) to have explicit modifier-key variants ("shift levels") for internationalization purposes:
* https://bugs.freedesktop.org/show_bug.cgi?id=11822

So after three years of silence and a little discussion, it got implemented in xkeyboard-config in June 2011. The new levels got filled with "VoidSymbol" as a placeholder:
* http://cgit.freedesktop.org/xkeyboard-config/commit/?id=062b5bfc

Saying "VoidSymbol" when you mean "F1" might be a bad idea, as some users noticed:
* https://bbs.archlinux.org/viewtopic.php?pid=1011464#p1011464

Fortunately there was already an obvious fix (2011 Oct):
* http://cgit.freedesktop.org/xkeyboard-config/commit/?id=1d1338afa
And people really did think it worked:
* https://bugs.archlinux.org/task/26414

Alas, some users still had symptoms:
* https://bugzilla.gnome.org/show_bug.cgi?id=661973

In September 2012, the discussion had a breakthrough:
* https://bugs.freedesktop.org/show_bug.cgi?id=45008#c23
...which led to changes in GTK+ and xkeyboard-config:
* http://git.gnome.org/browse/gtk+/commit/?id=314b6abb
* http://cgit.freedesktop.org/xkeyboard-config/commit/?id=a4f62448

And finally, after a system update this past November, I could—for the first time in over a year—use Shift+F3 to search backwards in my browser again.

Affected versions:
* xkeyboard-config 2.4.1 until 2.7
* gtk+ until 2.24.13 / 3.5.14
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