QT for some reason messes with XCompose causing broken input (Qt 5 only - Qt 4 did not break anything). In Qt 5.2 and 5.3 this was causing an invalid conversion in chat messages containing these resulting in the bad bytes being stripped. In Qt 5.9 it is still broken, but you at least get a string with something in it. This checks for non-zero converted strings for room creation and chat lines.
/*
** $Id: ltable.h,v 2.10.1.1 2007/12/27 13:02:25 roberto Exp $
** Lua tables (hash)
** See Copyright Notice in lua.h
*/
#ifndef ltable_h
#define ltable_h
#include "lobject.h"
#define gnode(t,i) (&(t)->node[i])
#define gkey(n) (&(n)->i_key.nk)
#define gval(n) (&(n)->i_val)
#define gnext(n) ((n)->i_key.nk.next)
#define key2tval(n) (&(n)->i_key.tvk)
LUAI_FUNC const TValue *luaH_getnum (Table *t, int key);
LUAI_FUNC TValue *luaH_setnum (lua_State *L, Table *t, int key);
LUAI_FUNC const TValue *luaH_getstr (Table *t, TString *key);
LUAI_FUNC TValue *luaH_setstr (lua_State *L, Table *t, TString *key);
LUAI_FUNC const TValue *luaH_get (Table *t, const TValue *key);
LUAI_FUNC TValue *luaH_set (lua_State *L, Table *t, const TValue *key);
LUAI_FUNC Table *luaH_new (lua_State *L, int narray, int lnhash);
LUAI_FUNC void luaH_resizearray (lua_State *L, Table *t, int nasize);
LUAI_FUNC void luaH_free (lua_State *L, Table *t);
LUAI_FUNC int luaH_next (lua_State *L, Table *t, StkId key);
LUAI_FUNC int luaH_getn (Table *t);
#if defined(LUA_DEBUG)
LUAI_FUNC Node *luaH_mainposition (const Table *t, const TValue *key);
LUAI_FUNC int luaH_isdummy (Node *n);
#endif
#endif