yes, I did. This approach is OK for online histogramming when it is
	possible to put all the variavles for histogramming into a relatively
	small array, however
	it is not so well suited for event display purposes: in this case one
	has to have almost all the  memory shared between main and display 
	processes.
	It would be much better to run display process as a thread (the same
	holds for the dialog - ideally dialog should be asynchronous!), 
	several years ago I even implemented this under MS/DOS.
	On UNIX however there is a caveat. Not all the flavours of UNIX support
	vfork, so whatever you do for example on IRIX, the job swap space 
	immediately doubles after you vfork a subprocess. May be it is
	not a problem - but it certainly requires some study.
 >   It should be since as I was constantly telling on this list ANY 
 > operation with Widget/Windows is an INTERACTIVE one and NEEDS some 
 > sort of even loop. 
 >    Leaving 
 > 
 >                 theApp.Run(kTRUE);
 > 
 >   one does leave the ROOT event loop so NO interactive operation is 
 > allowed at this point.
 > 
	It was just a matter of my ignorance and the lack of documentation:
	based on the documentation one can only guess what TCanvas::Close 
	and TCanvas::Delete really do and what is the differentce between 
	TCanvas::Delete and operator delete. As Rene pointed out there is a
	way to make the code reentrant...
...this is from your second mail:
>
>    By the way did you try your example under Windows. Under Windows 
> the event loop is impleneted as a separated thread of the main 
> application and leaving  theApp.Run(kTRUE); doesn mean closing that 
> thread (anyway I hopt i could be fixed).
>
	Unfortunately CDF doesn't have any NT-running platform... 
	I agree, having a thread seems to me to be a right thing.
						Pasha.