problems with screen redraws?

[Fairlight]

I'm having an odd problem with ncurses 5.4.

I'm creating a line with sprintf() that is always the same length.

I use mvwaddstr to place the line over the top of a previous line.  The
problem is that I'm doing something similar to `top`--a monitor program.
Well, the lines occasionally get shifted over one space at the start
position. I specify 0 and it starts at 1.  I specify 1, it starts at 2.
But only sporadically, and not all rows do it.  Different rows also do
this.

It also seems to bugger the percentage I have further out in that line,
showing file completion.  I thought this was due to the shifting, but when
the line is drawn over, it's not corrected.

I've tried a wmove to 0 and a clrtoeol of the entire line.  No good.  I've
tried moving to the start of the area where all the rows go and doing
clrtobot and still no go.

I should probably mention that I'm using ncurses through the perl Curses
module, but I believe this is a problem with the underlying library, not
the module.  It's like it's confused about its optimisations.  Even using
touchline or touchwin doesn't help though.  :(

Cobalt linux, 2.2 kernel.  ncurses 5.4.  Running the application through
ssh to PuTTY.  Oh, and I'm running it inside screen, if that matters.

Any pointers would help.  I'm not sure it's a bug, or if I'm just that
rusty with curses (it's been about 9 years).  What I'm doing appears to
work--for a while...until you get one going weird.  And the faster I do the
updates (the refreshes are timed in intervals) the more likely it seems to
be that this occurs.

mark->
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