
Crash occurs during the display of the PSTH, when nspikes > 1200.
Why 1200?

It has to do with freeing bpw->qplot.pix in atplotter (seemingly).  
Possibly it has already been freed?  This occurs at Attach(), 
QuadBarPlot.c:348.

I was trying to trace when bpw->qplot.pix might have been freed, and
not set to NULL by putting breakpoints on its XtFree and XtMalloc 
statements in QuadBarPlot.c.  So far without success.

What should happen if you free already freed memory?

Heres the appropriate part of the backtrace:

tracer_update(), unittrace.c:701
tracer_update_histograms(), unittrace.c:615
athisto_update(), atgraph.c:225
AtQuadPlotAttachData(), QuadPlot.c:297
Attach(), QuadBarPlot.c:348


