Petre yesterday I was trying to resolve issue
39944 and issue 39783 by calling the fold
maintainers directly instead of posting to RP
(when pane.setDocument() is called and the view
hierarchy is being constructed which in turn
triggers the fold hierarchy to be created).

It looked well until Mato hit a dedlok (attached).
I guess that happened when the IDE was shutdown
with few editors opened and Mato restarted the IDE
and "scrolled" through opened components by
Alt+Right key.
 That deadlock unveils an interesting case that
makes me think about the assigning of the document
to the text component.

In the current state the situation may be like this:
1) document gets created in CES.
2) document loading gets scheduled into RP.
3) before doc-loading RP write-locks the doc the
AWT thread constructs the editor pane and calls
CES.getDocumentHack() and assigns the doc into
pane by pane.setDocument().
4) setDocument() triggers various listeners (e.g.
in TextUI) that service the doc change - e.g. view
hierarchy gets created etc. Those operations
typically run under read/write lock being held on
the document to make sure there is no modification
done to the doc during e.g. view hierarchy
construction.
5) If any code involved would call
CES.openDocument() when under read/write lock
there is a deadlock because CES will put this
thread to sleep but as the thread still holds
read/write lock on the doc the doc-loading RP
cannot acquire the doc write lock and the loading
will never proceed. In the attached dedlok the
JavaParserGlue calls the CES.openDocument().

I was wondering whether it's necessary to assign
the document to text component prior it gets fully
loaded and I think it does not help much because
even if the document gets assigned to the
component the loading will write-lock it until
it's fully loaded so the user will see the content
_after_ the loading ends anyway (the repainting of
the editor acquires read-lock so it will block
until write-lock of loading RP gets released).
 I propose to change the current
CloneableEditor.initialize() to call
CES.openDocument() instead of
CES.getDocumentHack(). Although by openDocument()
we may block AWT for a while the user IMHO is
waiting for the document to be opened and she
would not do any useful work in the meantime anyway.

I've prepared a patch that I have tested and there
seem to be no problems with it. If you agree that
this would be useful change please approve it or
integrate it directly. Thanks.