simple (?!) redisplay question

[barmar@Think.COM (Barry Margolin)]

    Date: Wed, 27 Jun 90 11:52 PDT
    From: maglio%cogsci@ucsd.edu (Paul Maglio)

    The question is, why---when I switch configurations---do all my
    presentations blink?  I understand that it does redisplay in
    several passes, but why does it erase and then redisplay each
    object?  Perhaps I'm doing something wrong.  If I had sources I
    could tell better.  (I am running Genera 7.4 on a MacIvory).   

Apparently the DW:SET-PROGRAM-FRAME-CONFIGURATION function doesn't trust
that the saved bit array of a pane is correct, so it clears it and tells
it to redisplay from scratch.  Here's a couple of ways to see this in
action from your Circles demo:

1) Draw some circles.
   Select [Other Configuration].
   Select [Delete All Circles].
   Select [Other Configuration].

The old circles will show up for a moment and then disappear.

2) Draw some circles.
   Hit <Suspend>.
   Type some commands, to produce output on the display pane.
   Hit <Resume>.
   Select [Other Configuration] twice in a row.

When it returns to the first configuration you'll briefly see the output
from your suspend session, then the pane will clear and redisplay the
circles.

                                                barmar