Re: Chgat() Functions Erase Pad Characters

[Thomas Dickey]

On Sun, Jan 08, 2017 at 12:53:47AM -0500, Grady Martin wrote:
> Hello, and curse all of you.
> 
> The chgat() family of functions erase characters on stdscr that originate
> from pads.  Why?  Am I missing something in my code?  Please see the attached
> demonstration program.

The data owned by the pad isn't shared with the standard screen (stdscr)

The manpage:

       A pad is like a window, except that it is not restricted by the  screen
       size,  and  is not necessarily associated with a particular part of the
       screen.  Pads can be used when a large window is  needed,  and  only  a
       part  of  the  window will be on the screen at one time.  Automatic re‐

The mvchgat updates the standard screen, and the wgetch causes a refresh
on the standard screen.

So the updates to the standard screen overwrite the pad.

Think of it as something like a newwin - making updates and refreshing
one window will overwrite other windows that it happens to overlap.

-- 
Thomas E. Dickey <address@hidden>
http://invisible-island.net
ftp://invisible-island.net

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