title: Empty string in Delphi / Windows combo box causes access exception
body: <p>I've got a Delphi 7.0 application that throws a memory access exception / message box every time it writeln's an empty string from the string list associated with a combo box:</p>
  
  <pre><code>csvstrlst := combobox1.Items;
  
  csvstrlst.clear;
  csvstrlst.add('');    //problem
  csvstrlst.add('a');   //no problem
  csvstrlst.add('');    //problem
  csvstrlst.add('b');   //no problem
  
  //throws memory access messages (I think the writeln writes a line though)
  for n := 1 to csvstrlst.Count do begin
      writeln(out_file,csvstrlst.strings[n-1])
  end;
  
  //throws memory access messages (writeln does write a comma text string though)
  writeln(out_file,csvstrlst.commatext);
  </code></pre>
  
  <p>Running on Windows 7 or XP. As application or in D7 IDE. Combobox with empty string items also causes the same error if the parent of the form it is on is changed.</p>
  
  <p>Has anyone else ever seen or heard of this problem? Any other information available at all?</p>