bug found when freeing screen(s)

[Frédéric Boiteux]

    Hello,

When porting an own application using ncurses from an old 5.5 version to
a current 5.7 (from Debian Lenny system), I found a bug related to free
of screens (the application manages multiple terminals) : when the close
of terminals was in the same order they was created, the application
segfaulted or looped indefinitely. I identified the bug in the
delscreen() function, and more precisely in delink_screen() where the
global list of screens is incorrectly updated.
  I've successfully tested my application with the simple patch attached.

  I think the bug is already present in latest version of ncurses.

  Could you validate my analyze and proposed resolution ?

     with regards,
        Fred

bug_free_delscreen.patch
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