- modify to work with ncurses' threaded-library, which does not allow assignment to LINES/COLS (report by Marcus Roeckrath).
- correct clearing after text in progressbox from 2018/06/21 changes for resizing (reports by David Boyd, Alan Somers).
- improved configure macros CF_GNU_SOURCE, CF_POSIX_C_SOURCE, CF_XOPEN_SOURCE
- update config.guess, config.sub
My shell script that needs dialog is working.