How can I disable the ISO14755 shift-ctrl hotkey?

[Adam Spiers]

On Sat, Mar 07, 2009 at 12:03:35AM +0100, Gregor Zattler wrote:
> * Thomas Adam <thomas.adam22 at gmail.com> [02. Mär. 2009]:
> > 2009/3/2 Gregor Zattler <telegraph at gmx.net>:
> >> * Gregor Zattler <telegraph at gmx.net> [25. Aug. 2007]:
> >>> * Yin Wang <shredderyin at gmail.com> [22. Apr. 2006]:
> >>>> I'm using Emacs inside rxvt-unicode. Often I use something like a
> >>>> Control+Shift combination. For example C-@ (set-mark-command) is
> >>>> actually Control+Shift+2 on my keyboard. Because urxvt captured
> >>>> Control+Shift, this key stops to function in my Emacs. If I press this
> >>>> key, the small window "ISO 14755 mode" appears, which is very
> >>>> annoying. I can't disable this window even using --disable-iso14755 in
> >>>> configure.
> >>> [...]
> >>>> Is there a way to turn this feature off completely?
> >>>
> >>> Last year Ilya Voyager Schurov sugggested to hack the source
> >>> code.  Isn't there any other way of disabeling the whole feature?
> >>> I start urxvt with ++iso14755_52 but this only stops the "Keycap
> >>> picture insert mode" window but not the "ISO 14755 mode" window.
> >>> Any ideas other than hacking the code -- which I'm not able to
> >>> do?
> >>
> >> Any idea on this problem?  I now use emacs org mode which heavily
> >> relies on ctrl-shift key combos.
> > 
> > ./configure --disable-iso14755
> 
> That's a bit inconvinient but yes: it works for rxvt.  Alas,
> emacs started in a terminal does not recognize shift+ctrl key
> combos.  Back to square one...

Did anyone figure this out?  I also want to disable it and have
shift+ctrl passed through to emacs.  According to the man page you can
disable via an X resource rather than the inconvenience of recompiling:

       iso14755_52: boolean
           Turn on/off ISO 14755 5.2 mode (default enabled).

but I tried both

  URxvt*iso14755_52: false

and

  URxvt.iso14755_52: false

and neither made no difference.

Thanks,
Adam