# Screen() problem in latest Psychtoolbox for MacOS X

**URL:** <https://psychtoolbox.discourse.group/t/screen-problem-in-latest-psychtoolbox-for-macos-x/2071>\
**Category:** Uncategorized\
**Created:** [February 20, 2004, 4:50pm UTC](https://psychtoolbox.discourse.group/t/screen-problem-in-latest-psychtoolbox-for-macos-x/2071 "2004-02-20T16:50:02Z")\
**Posts on this page:** 1\
**Page:** 1

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**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:** [February 20, 2004, 4:50pm UTC](https://psychtoolbox.discourse.group/t/screen-problem-in-latest-psychtoolbox-for-macos-x/2071/1 "2004-02-20T16:50:02Z")

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Hi,  
  
we run the latest Psychtoolbox for OSX on 10.3.3. However  
was it not possible to use the Screen-Function properly.  
All we get is a black screen when calling something like  
Screen('OpenWindow', 0, 150);  
  
When we try to call it like: Screen('OpenWindow', 0, [1 1  
1]); we get the error: "Unable to coerce color".  
Strangly enough it "works" (at least creates a black  
screen) when calling it with 4 values.  
  
Maybe there is a difference in the way the newest OSX  
version handels the screen-calls, we don't know.  
  
Another strange thing we noticed is an inconsistency in the  
sequence of parameters for Screen. The source says:  
Screen('Windowcommand', Screennumber, [Color},...). The  
traditional way is to first give the screennumber and then  
the windowcommand. Both work (or rather don't work) the  
same way.  
  
Thanks in advance,  
Thomas  
  
P.S. also there is no help-file for screen.