While looking for the cause of this bug, I found it is a problem in xaw3dg, that it frees the memory given when setting XtNString when international is set. I've stolen the attached difference to libXaw, which fixes this.
That seems to be just the same problem and fix as in 438737, therefore I'm merging this. (I wished I'd seen the other bugreport earlier, that had saved me almost an hour of source reading and debugging...) Hochachtungsvoll, Bernhard R. Link
diff -u -r xaw3d-1.5+E/lib/Xaw3d/MultiSrc.c xaw3d-1.5+E.patched/lib/Xaw3d/MultiSrc.c --- xaw3d-1.5+E/lib/Xaw3d/MultiSrc.c 2007-09-08 13:44:47.000000000 +0200 +++ xaw3d-1.5+E.patched/lib/Xaw3d/MultiSrc.c 2007-09-08 13:45:38.000000000 +0200 @@ -739,6 +739,7 @@ if ( string_set || (old_src->multi_src.type != src->multi_src.type) ) { RemoveOldStringOrFile(old_src, string_set); + src->multi_src.allocated_string = old_src->multi_src.allocated_string; file = InitStringOrFile(src, string_set); /* Load pieces does this logic for us, but it shouldn't. Its messy.*/