Comment 1 for bug 512547

Same issue occurs on OS X 10.5.8, using 10.4 Build. The stack trace is a bit different:

java.io.FileNotFoundException: /Users/jowillia/temp (No such file or directory)
 at java.io.FileOutputStream.open(Native Method)
 at java.io.FileOutputStream.<init>(FileOutputStream.java:179)
 at java.io.FileOutputStream.<init>(FileOutputStream.java:70)
 at java.io.FileWriter.<init>(FileWriter.java:46)
 at edu.mit.csail.uid.SikuliPane.saveAsFile(SikuliPane.java:126)
 at edu.mit.csail.uid.SikuliPane.saveFile(SikuliPane.java:100)
 at edu.mit.csail.uid.SikuliIDE$FileAction.doSave(SikuliIDE.java:417)
 at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
 at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
 at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
 at java.lang.reflect.Method.invoke(Method.java:592)
 at edu.mit.csail.uid.SikuliIDE$MenuAction.actionPerformed(SikuliIDE.java:350)
 at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1882)
 at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:22save to /Users/jowillia/temp/
02)
 at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:420)
 at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:258)
 at javax.swing.AbstractButton.doClick(AbstractButton.java:334)
 at apple.laf.ScreenMenuItem.actionPerformed(ScreenMenuItem.java:95)
 at java.awt.MenuItem.processActionEvent(MenuItem.java:597)
 at java.awt.MenuItem.processEvent(MenuItem.java:556)
 at java.awt.MenuComponent.dispatchEventImpl(MenuComponent.java:298)
 at java.awt.MenuComponent.dispatchEvent(MenuComponent.java:286)
 at java.awt.EventQueue.dispatchEvent(EventQueue.java:466)
 at java.awt.EventDispatchThread.pumpOneEventForHierarchy(EventDispatchThread.java:269)
 at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:190)
 at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:184)
 at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:176)
 at java.awt.EventDispatchThread.run(EventDispatchThread.java:110)

But there is a work around. If you end the file in .sikuli, the the file is created and the script and images are stored. This of course only tested on OS X.