procedure ShowMultiColumns(FileListBox: TFileListBox; bValue: Boolean);
begin
with TDirectoryListBox(FileListBox) do
begin
Columns := Ord(bValue) and (Ord(bValue) and 1);
SendMessage(Handle, LB_SETCOLUMNWIDTH, Canvas.TextWidth('WWWWWWWW.WWW'), 0);
end;
end;
{Example:}
procedure TForm1.Button1Click(Sender: TObject);
begin
ShowMultiColumns(FileListBox1, True);
end;