http://doc.trolltech.com/3.3/qfile.html#open
IO_Append Opens the file in append mode. (You must actually use (IO_WriteOnly | IO_Append) to make the file writable and to go into append mode.) This mode is very useful when you want to write something to a log file. The file index is set to the end of the file. Note that the result is undefined if you position the file index manually using at() in append mode.