[Interest] Debugging helpers in Ubuntu

[André Pönitz]

On Mon, Jan 23, 2017 at 11:29:26AM +0100, Viktor Engelmann wrote:
> If it has to do with certain variables, then that only makes sense if
> the "locals and expressions" panel wants to display an object that has
> been deleted already, so there would be a dangling pointer. Does that
> happen in your code or Qt code? If Qt, can you tell which methods?

It happens(/ed) when during the evaluation of the python code that
produces the display data for a (sub-)variable or some "evaluated
expression" another segmentation fault was triggered.

In general, that is expected and conceptually unavoidable behaviour
for uninitialized data (happens typically in C++ debugging before the 
constructor of some local variable is executed) or for "properly"
corrupted data (at any time).

There had been safeguards in place to handle those sitation since the
beginning, but that had been partially canceled by some generic changes
to message box handling. What was left went unnoticed with the default
settings for a while, but got more prominent with 4.2[.0] when the
QObject guts display was switched on by default. 

Andre'