private
   mword: string;
public
....
...
procedure TForm1.dbGrid1Press(Sender: TObject; var Key: Char);
          var mlen: integer;
begin
     if length(mword)>2 then setlength(mword,0);
     try
        mword:= mword Key;
        if IsDBCSLeadByte(Byte(mword[2])) then begin
           Edit1.Text:= Edit1.Text mword;
           setlength(mword,0);
        end
        else if (Key in ['0'..'9']) or
           (Key in ['a'..'z']) or
           (Key in ['A'..'Z']) or
           (Key in ['`','~','!','@','#','$','%','^','&','*','(',')','-','_',
                    ' ','=','|','\',',','<','.','>','/','?',';',':','[','{',
                    ']','}']) or
           (ord(Key)=32) or (ord(Key)=39) or (ord(Key)=34) then
        begin
           Edit1.Text:= Edit1.Text Key;
           setlength(mword,0);
        end
        else if (ord(Key)=8) and (length(Edit1.Text)>0) then  // VK_BACK
        begin
           mlen:= length(Edit1.Text);
           if IsDBCSLeadByte(Byte(Edit1.Text[mlen])) then
              Edit1.Text:= copy(Edit1.Text,1,mlen-2)
           else Edit1.Text:= copy(Edit1.Text,1,mlen-1);
           setlength(mword,0);
        end;
     except
        setlength(mword,0);
     end;
end;