There is a file called "RWMFixUnit.pas" that contains the hack, it replaces the call to RWM in the Controls unit and uses the GlobalAtom value (that will get cleaned up) 
instead of the leaky RWM. You HAVE to add this unit before the Controls (otherwise it will complain!) and it will only work in statically linked applications. 
I have simplified the implementation, so it will just reuse the global atom for the "ControlOfs" leak, all other RWM allocation will proceed as normal.

function IntrRegisterWindowMessage(lpString: PWideChar): UINT; stdcall;

begin

     Result := 0;

     try

       if Pos('ControlOfs',lpString) = 1 then Result := GlobalFindAtom(lpString);

       //This is for defensive reasons... not really needed

       if Result = 0 then

       begin

          //if we get here we know that the GlobalAtom has not been allocated yet

          //so this is ***not*** the leaky ControlOfs RWM as Atom

          if @OrgRWMPtr <> nil then

               Result := OrgRWMPtr(lpString);

function IntrRegisterWindowMessage(lpString: PChar): UINT; stdcall;

begin

     Result := 0;

     try

       if Pos('ControlOfs',lpString) = 1 then Result := GlobalFindAtom((lpString));

       //This is for defensive reasons... not really needed

       if Result = 0 then

       begin

          //if we get here we know that the GlobalAtom has not been allocated yet

          //so this is ***not*** the leaky ControlOfs RWM as Atom

          if @OrgRWMPtr <> nil then

               Result := OrgRWMPtr(PWideChar(lpString));