Bug in ProbeDisplay notification?

[glen e. p. ropella]

Wojciech Kopczuk writes:
 > 1. probe display for an object is created 
 > 2. it is removed by user from the GUI (pressing the red button on 
 > the probe)
 > 3. at some later point the object itself is dropped -> system crashes
 > 
 > I have traced it using gdb - crash takes place in method 
 > dropAllocations invoked from Object's method drop, more precisely
 > in the line 161 of the file DefObject.m:
 > suballocEntry->notifyFunction( self, nil, suballocEntry->argument );
 > 'notifyFunction' is 'notifyObjectDropped' function defined in 
 > module ProbeDisplay.m - when I enter it and try to print its third
 > argument 'pd'
 > in gdb (p *pd) I get:
 >  {class_pointer = 0xffffffff}
 > and then [pd drop] is invoked...
 > My guess is that while ProbeDisplay is dropped earlier, a reference
 > to it is not removed  so there is an attempt to drop it again when
 > an object itself is being dropped.
 > I am pretty sure the problem is not due to my application, the 
 > same code compiled with Swarm 1.0.0 didn't crash.
 > Wojtek

Yep! This sounds like a bug.  What I need to do is put a hook
in the ProbeDisplay that will remove the allocation reference
from the target object if the probedisplay is removed via some
other mechanism (i.e. the object will persist but the display
won't).

I'll check on it and provide a patch.

glen