Created attachment 100180 [details]
jstack dump

Created attachment 100181 [details]
messages.log for deadlock

The main issue here is (IMO) that a component opening is blocked, because an exception is thrown in the background opening thread (see the messages.log). I have modified the GoToTypeAction to use NbDocument.findRecentEditorPane, but that does not fix the actual problem:
http://hg.netbeans.org/jet-main/rev/ccbabb58e60d

Also, I think that EditorCookie.getOpenedPanes should be deprecated (although there is no 100% replacement), as I do not know about any use case when the use of this method would be correct after the lazy editor opening - is there such a usecase?

Integrated into 'main-golden', will be available in build *201007030001* on http://bits.netbeans.org/dev/nightly/ (upload may still be in progress)
Changeset: http://hg.netbeans.org/main/rev/ccbabb58e60d
User: Jan Lahoda <jlahoda@netbeans.org>
Log: #187747: (partial) do not use EditorCookie.getOpenedPanes.

This is not a 6.9.1 blocker IMHO. Making it P2.

I would like someone from VCS team to evaluate whether the exception from the log:

INFO [org.netbeans.modules.mercurial]: execEnv():  execEnv(): IOException
java.io.IOException: java.io.IOException: error=2, Arquivo ou diretório não encontrado
	at java.lang.UNIXProcess.<init>(UNIXProcess.java:148)
	at java.lang.ProcessImpl.start(ProcessImpl.java:65)
	at java.lang.ProcessBuilder.start(ProcessBuilder.java:453)
Caused: java.io.IOException: Cannot run program "hg": java.io.IOException: error=2, Arquivo ou diretório não encontrado
	at java.lang.ProcessBuilder.start(ProcessBuilder.java:460)
	at org.netbeans.modules.mercurial.util.HgCommand.exec(HgCommand.java:2887)
	at org.netbeans.modules.mercurial.util.HgCommand.execEnv(HgCommand.java:2839)
	at org.netbeans.modules.mercurial.util.HgCommand.execForVersionCheck(HgCommand.java:3105)
	at org.netbeans.modules.mercurial.util.HgCommand.getHgVersion(HgCommand.java:598)
	at org.netbeans.modules.mercurial.Mercurial.checkVersionIntern(Mercurial.java:199)
	at org.netbeans.modules.mercurial.Mercurial.access$000(Mercurial.java:81)
[catch] at org.netbeans.modules.mercurial.Mercurial$1.run(Mercurial.java:190)
	at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:1418)
	at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:1957)

Is benign or malign during document opening. If it is benign please assign back. If it can actually cause the file not to open please handle as VCS bug. Thanks.

IMO it's unrelated.
The logged exceptions warns user that he has some folders under mercurial control, however no hg executable has been found. The check for hg version should not interfere with opening a file (i can't imagine how it could), it runs in a background thread and it's only result should be disabling mercurial actions in the IDE.

Ok, I will examine the AssertionError in 


java.lang.AssertionError
	at org.openide.text.CloneableEditor$DoInitialize.initNonVisual(CloneableEditor.java:571)
	at org.openide.text.CloneableEditor$DoInitialize.run(CloneableEditor.java:327)
	at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:1418)
	at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:1957)
Caused: org.openide.util.RequestProcessor$SlowItem: task failed due to
	at org.openide.util.RequestProcessor$Task.schedule(RequestProcessor.java:1456)
	at org.openide.text.CloneableEditor$DoInitialize.<init>(CloneableEditor.java:294)
	at org.openide.text.CloneableEditor.initialize(CloneableEditor.java:229)
	at org.openide.text.CloneableEditor.componentShowing(CloneableEditor.java:205)

I am sorry but I am marking this issue as fixed after just adding some more logging. If this happens again please turn on the logging via

-J-Dorg.openide.text.level=FINE

and attach the message log file again. Without more info we are unable to do more.

http://hg.netbeans.org/jet-main/rev/80577d258587