[ROOT] GUI classes with TThread

From: LEE, KERRY T. (JSC-SR) (UHCL) (kerry.t.lee1@jsc.nasa.gov)
Date: Tue Jan 20 2004 - 18:39:43 MET

ROOT team,

I sent this message last week and since I have been spoiled in the past
with quick replys I think it is possible that it has been overlooked. 

I use RH 9.0 gcc 3.2.2, and tried my program with ROOT versions 3.10.02
and 4.00.00 with the same results.


-----Original Message-----
From: owner-roottalk@pcroot.cern.ch
To: 'roottalk@pcroot.cern.ch'
Sent: 1/16/2004 4:46 PM
Subject: [ROOT] GUI classes with TThread

Dear ROOTers,

I am attempting to create an online histogram monitoring GUI, in which
histograms are filled , but only displaying a few at a time.  I
have a TListBox containing a list that selects which histograms are to
displayed, and a TROOTEnbededCanvas to display the histograms in.  This
worked perfectly as long as the histograms were finished being filled
my simulated online run).  While the run was in progress I could not
interact with the GUI and change the histogram display.  My next step
was to
introduce TThreads via the TThreadframe example.  Unfortunately I did
before coming across the previous message


which states that "Access to TCanvas, TPad and other graphics from
Does not work, even if access is locked explicitly.
It seems that the errors occur in the X event handling
outside root. Moving the mouse accelerates the crashes considerably."
to reading this I concluded (from stack dump) that there was probably
something wrong with X event handling.  My program ran fine as long as I
didn't select a different set of histograms to be displayed, and
occasionally I could display different histogram sets but a crash was
inevitable if I did that.  Further in the above mail it was stated that
problem was not likely to ever be fixed.

Therefore, if anyone has similar monitoring requirements I'd like to
how you overcame these problems.  Any help is appreciated.


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