bug: sorting by label causes errors
Use of uninitialized value in string eq at /home/djp/bin/taskopen.pl line 204, <CONFIG> line 26.
Use of uninitialized value in string comparison (cmp) at /home/djp/bin/taskopen.pl line 211, <CONFIG> line 26.
Use of uninitialized value in string eq at /home/djp/bin/taskopen.pl line 204, <CONFIG> line 26.
Use of uninitialized value in string eq at /home/djp/bin/taskopen.pl line 204, <CONFIG> line 26.
and so on, many lines of
