Re: [ROOT] Problem with TCanvas when using KDE 2.1

From: Brett Viren (bv@bnl.gov)
Date: Wed Aug 01 2001 - 15:56:57 MEST


Fons Rademakers writes:
 >   this fix is still in ROOT and I run myself always without backingstore
 > and don't see any problems (do you?). Maybe something goes wrong when 
 > Christian mixes the two versions. Version 3.00/01 still has the expose
 > events bug which was only fixed in 3.00/05.

I have been using "backingstore" all this time.  I just turned it off
and I get similar problems as described by Christian and Andreas.  I
am fairly certain that I am not mixing ROOT versions (which is from
CVS as of 2 days ago).

Besides observing the black and white "trail", I notice that the
TCanvas flickers.  I am guessing that ROOT is indeed doing a redraw
from a backing pixmap, but that somehow this pattern is getting drawn
to the pixmap before being flushed to the screen.

It is odd that it works for you.  Maybe "backingstore" is turned on
implicitly on your system?  Googling around I found the statement that
XFree86 4.0 or higher has the backing store disabled by default, which
implies that it is enabled by default in v3.  Do you run XFree86 v3 or
v4?

-Brett.



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