With reference to drools-setup discussion thread, I'm don't have the same scenario of Gergely which is open as DROOLS-672:

First of all: this problem can be reproduced with only a single audit file.

but I got a reproducer for the scenario I describe:

I'm experiencing similar behavior and stacktrace in the Eclipse log, when I get as a result several Audit logs file ( because of the many insert/fire etc therefore many audit records results in automatic file splits ).
When I have several audit logs, some logs do open in the Audit view correctly; other log files in the sequence do not open and as you describe Audit view is empty and that stacktrace output is produced in the Eclipse log.
Do you have the same experience?
I'm asking as you seem to mention about a single log file but I was wondering if it's actually one in a sequence of audit log.
I'm also wondering if this is due to the log containing some cross-reference to other log records not appearing in this file instance but the previous/next, making the java code which is constructing the items in the Audit log treeview fail with that stacktrace.

It could be the solution to this bug/reproducer will solve the same issue as Gergely, but I cannot tell if our cases are really the same hence I prefer to raise this as a new separate JIRA bug record.

Steps to reproduce

With reference to attached reproducer

the first sessionlog.log log file opens correctly.

From log file sessionlog1.log it will no longer open, Audit view blank, causing the stacktrace error in Eclipse workspace log (ref. below).
The log file sessionlog1.log starts with event:

<org.drools.core.audit.event.ObjectLogEvent>
  <type>3</type

No other log files in the sequence 1-22 will open.

Until sessionlog23.log, which starts with event:

<org.drools.core.audit.event.ActivationLogEvent>
  <type>4</type>

The log files in the sequence 23-44 will open again.

Until stop to display again from log file sessionlog45.log, which starts with

<org.drools.core.audit.event.ActivationLogEvent>
  <type>7</type>

when Audit view blank, in the Eclipse workspace log (under workspace/.metadata) will display this or analogous:

The eclipse workspace log stacktrace when trying to open in Audit view one "out of sequence" log

!ENTRY org.eclipse.ui 4 0 2015-01-29 15:04:06.339
!MESSAGE Unhandled event loop exception
!STACK 0
java.util.EmptyStackException
	at java.util.Stack.peek(Unknown Source)
	at java.util.Stack.pop(Unknown Source)
	at org.drools.eclipse.debug.AuditView.createPhreakEventList(AuditView.java:238)
	at org.drools.eclipse.debug.AuditView.refresh(AuditView.java:150)
	at org.drools.eclipse.debug.AuditView.setLogFile(AuditView.java:104)
	at org.drools.eclipse.debug.actions.FileAuditDropAdapter.performDrop(FileAuditDropAdapter.java:39)
	at org.eclipse.jface.viewers.ViewerDropAdapter.drop(ViewerDropAdapter.java:254)