File selection dialog fails

[mecworks]

In Ipython, the first call to pythonzenity.FileSelection() fails with the following error:

In [1]: from common import pythonzenity
In [2]: pythonzenity.FileSelection()
/home/dir/prog/common/pythonzenity/python_zenity.py:452: GtkWarning: IA__gtk_file_chooser_get_files: assertion `GTK_IS_FILE_CHOOSER (chooser)' failed
return file.dialog.get_filename()

On subsequent calls, the command silently returns and again, does not return any selected files.