alice-teacher SceenShots and Mac

[Rikki Fletcher]

My Mac student tells me she cannot get "take picture" to work.  Seems fine
in Windows.  Is there an issue?  She downloaded the latest version of
Alice.  Here's the beginning of the error:
Error while storing screen capture.
Alice version: 2.2 08/05/2011
Throwable that caused the error:
java.lang.NullPointerException
at edu.cmu.cs.stage3.image.ImageUtilities.getWidth(ImageUtilities.java:43)
at edu.cmu.cs.stage3.image.ImageIO.store(ImageIO.java:106)
at edu.cmu.cs.stage3.image.ImageIO.store(ImageIO.java:103)
at
edu.cmu.cs.stage3.alice.authoringtool.AuthoringTool.storeCapturedImage(AuthoringTool.java:28