NPE occurs when renaming an element in source view.
It's a regression from
070129_5, i.e. with 070129_5 + jdk1.6, the issue occurs only on
non-winXP.  with 070130_3 + jdk1.6, it occurs on winXP as well.

>System Info: 
  Product Version         = NetBeans IDE 5.5.1 (Build 200701300600)
  Operating System        = Linux version 2.6.17-10-generic running on i386
  Java; VM; Vendor; Home  = 1.5.0_10; Java HotSpot(TM) Client VM 1.5.0_10-b03; 

Steps to reproduce:
Open an xml schema.
Switch to source view.
Rename an element.

The following exceptions are thrown:

*********** Exception occurred ************ at 12:02 PM on Jan 30, 2007
java.lang.NullPointerException
        at
org.netbeans.modules.bpel.core.completion.BpelCompletionModelProvider.isBpelFile(BpelCompletionModelProvider.java:75)
        at
org.netbeans.modules.bpel.core.completion.BpelCompletionModelProvider.getModels(BpelCompletionModelProvider.java:44)
        at
org.netbeans.modules.xml.schema.completion.util.CompletionContextImpl.initModels(CompletionContextImpl.java:363)
        at
org.netbeans.modules.xml.schema.completion.CompletionQuery.query(CompletionQuery.java:67)
        at
org.netbeans.spi.editor.completion.support.AsyncCompletionTask.run(AsyncCompletionTask.java:195)
        at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:499)
[catch] at
org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:932)
*********** Exception occurred ************ at 12:02 PM on Jan 30, 2007
java.lang.NullPointerException
        at
org.netbeans.modules.editor.structure.api.DocumentModel$DocumentModelModificationTransaction.access$100(DocumentModel.java:815)
[catch] at
org.netbeans.modules.editor.structure.api.DocumentModel$2.run(DocumentModel.java:460)
        at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:461)
        at
java.awt.EventDispatchThread.pumpOneEventForHierarchy(EventDispatchThread.java:242)
        at
java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:163)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:157)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:149)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:110)