Missing Po file for "key_button.cxx"

[Gervase Lam]

I get the following error while compiling a fresh Pingus:

c++ -DHAVE_CONFIG_H -I. -I. -I../../..   -I/usr/include/libxml2/libxml 
-I/usr/include/libxml2  -g -O2 -c -o joystick_button.o `test -f 
joystick_button.cxx || echo './'`joystick_button.cxx
source='key_button.cxx' object='key_button.o' libtool=no \
depfile='.deps/key_button.Po' tmpdepfile='.deps/key_button.TPo' \
depmode=gcc3 /bin/sh ../../../depcomp \
c++ -DHAVE_CONFIG_H -I. -I. -I../../..   -I/usr/include/libxml2/libxml 
-I/usr/include/libxml2  -g -O2 -c -o key_button.o `test -f key_button.cxx 
|| echo './'`key_button.cxx
make[4]: *** No rule to make target `key_helper.cxx', needed by 
`key_helper.o'.  Stop.

Basically there is no Po file for "key_button.cxx", which contains the 
make rules for making the file.  Anybody care to own up!

I'm extremely tempted to make the Po file myself.  However, somebody else 
might problably know more quickly what is needed in the Po file.

Thanks,
Gervase.