Created attachment 3140 [details]
Dump stack when IDE was frozen

It's probably inevitable (unless there's some bug I haven't found
yet): there's a time window between the source model gets garbage
collected, but before the reference queue is polled and the parsing
support notices that its data is gone [this is a periodical task in
OpenIDE-Request-Processor]. If you hit such a window, then the AWT was
fooled by OK status of the model, but blocked because the reference
was already cleared. 
However this race should happen quite rarely, possibly when other
tasks keep the RequestProcessor busy for a long time. If the issue
appears regularly, please reopen the bug.

This type of error has been occurring often in our 
NetBeans 3.3.2-based product OptimalJ 2.2.
In our case the interesting portion of the stack trace was:

"OpenIDE Request Processor-0" daemon prio=2 tid=0x0098D9B8 
nid=0x6e4 waiting on
monitor [2160f000..2160fdb4]
        at java.lang.Object.wait(Native Method)
        - waiting on <03B2F7E0> (a java.awt.EventQueue$1
$AWTInvocationLock)
        at java.lang.Object.wait(Object.java:426)
        at java.awt.EventQueue.invokeAndWait
(EventQueue.java:794)
        - locked <03B2F7E0> (a java.awt.EventQueue$1
$AWTInvocationLock)
        at org.openide.util.Mutex.doEventAccess
(Mutex.java:928)
        at org.openide.util.Mutex.readAccess
(Mutex.java:162)
        at org.netbeans.core.NbTopManager.createDialog
(NbTopManager.java:350)
        at 
org.netbeans.modules.web.context.WebContextObject.showNotif
yDialog(We
bContextObject.java:825)
        at 
org.netbeans.modules.web.context.WebContextObject.mkProject
View(WebCo
ntextObject.java:244)
        at 
org.netbeans.modules.web.context.WebContextObject.access$00
0(WebConte
xtObject.java:78)
        at 
org.netbeans.modules.web.context.WebContextObject$1.run
(WebContextObj
ect.java:135)
        at org.openide.util.Task.run(Task.java:152)
        at 
org.openide.util.RequestProcessor$ProcessorThread.run
(RequestProcesso
r.java:622)

"AWT-EventQueue-0" prio=7 tid=0x1EE06360 nid=0x6e8 waiting 
on monitor [20a6e000.
.20a6fdb4]
        at java.lang.Object.wait(Native Method)
        - waiting on <03A26748> (a 
org.openide.util.RequestProcessor$Task)
        at java.lang.Object.wait(Object.java:426)
        at org.openide.util.Task.waitFinished(Task.java:86)
        - locked <03A26748> (a 
org.openide.util.RequestProcessor$Task)
        at 
org.openide.util.RequestProcessor$Task.waitFinished
(RequestProcessor.
java:432)
...

I'm fixing this now (I think) by moving 2 lines of code 
into an already existing "invokeLater":
        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                d[0] = TopManager.getDefault 
().createDialog (descriptor); // moved
                d[0].setSize (580, 180); // moved
                d[0].show ();
            }});
in WebContextObject.showNotifyDialog (package 
org.netbeans.modules.web.context).

Resolved for 3.3.x or earlier, no new info since then -> closing.

Resolved for 3.4.x or earlier, no new info since then -> closing.