# SCREEN('CopyWindow') wait for veritcal synch?

**URL:** <https://psychtoolbox.discourse.group/t/screen-39-copywindow-39-wait-for-veritcal-synch/1940>\
**Category:** Uncategorized\
**Created:** [January 8, 2002, 10:14pm UTC](https://psychtoolbox.discourse.group/t/screen-39-copywindow-39-wait-for-veritcal-synch/1940 "2002-01-08T22:14:55Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![Allen\_Ingling](https://avatars.discourse-cdn.com/v4/letter/a/a183cd/32.png) [@Allen\_Ingling](https://psychtoolbox.discourse.group/u/Allen_Ingling)\
**Post date:** [January 8, 2002, 10:14pm UTC](https://psychtoolbox.discourse.group/t/screen-39-copywindow-39-wait-for-veritcal-synch/1940/1 "2002-01-08T22:14:55Z")

</div>

When an OffScreenWindow is copied to the monitor output (Screen 0), does   
SCREEN('CopyWindow') wait for a vertical synch before changing the monitor   
output? I hope I posed the question correctly. I am asking on the behalf of   
someone else, and he referred to the RSVP visual stimulus software which he said  
does wait for a vertical synch signal before changing the display. Thanks for   
any help you can offer.  
  
- Dan

---

<div class="post-metadata">

**Author:** ![Allen\_Ingling](https://avatars.discourse-cdn.com/v4/letter/a/a183cd/32.png) [@Allen\_Ingling](https://psychtoolbox.discourse.group/u/Allen_Ingling)\
**Post date:** [January 9, 2002, 12:34am UTC](https://psychtoolbox.discourse.group/t/screen-39-copywindow-39-wait-for-veritcal-synch/1940/2 "2002-01-09T00:34:44Z")

</div>

> \>When an OffScreenWindow is copied to the monitor output (Screen 0), does  
> \>SCREEN('CopyWindow') wait for a vertical synch before changing the monitor  
> \>output? I hope I posed the question correctly. I am asking on the behalf of  
> \>someone else, and he referred to the RSVP visual stimulus software   
> \>which he said  
> \>does wait for a vertical synch signal before changing the display. Thanks for  
> \>any help you can offer.

Doesn't wait. But you can code  
  
SCREEN(w,'WaitBlanking'); SCREEN(w,'CopyWindow',...);  
  
to achieve the desired effect.