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Changes between Initial Version and Version 1 of Ticket #4019, comment 2

initial	v1
1	1	Before [37ffc024225fd2ef1016babf3cbbeabce4a32899] we had `mc_global.tty.winch_flag` that was set in `sigwinch_handler()`, than it checked some times (note: checked but no reset) and finally reset in `dialog_change_screen_size()`.
2	2
3		Currently we have `tty_got_winch()` function that checks whether SIGWINCH was raised. But this function has side effect: the virtual SIGWINCH flag is reset after read. 'Virtual flag' means the non-emptiness of FIFO. If `tty_got_winch()` is sequentially called several times, only first call can return TRUE (FIFO was not emty at this moment), other calls return FALSE (read from an empty FIFO). Finally, `dialog_change_screen_size()` may not be called in dialog event loop in `frontend_dlg_run()`. Such case we have if SIGWINCH is raised while subshell is active.
	3	Currently we have `tty_got_winch()` function that checks whether SIGWINCH was raised. But this function has side effect: the virtual SIGWINCH flag is reset after read. 'Virtual flag' means the non-emptiness of FIFO. If `tty_got_winch()` is sequentially called several times, only first call can return TRUE (FIFO was not empty at this moment), other calls return FALSE (read from an empty FIFO). Finally, `dialog_change_screen_size()` may not be called in dialog event loop in `frontend_dlg_run()`. Such case we have if SIGWINCH is raised while subshell is active.
4	4
5	5	I've tried fix that in