При переходе от бранча 4.1 к бранчу 5.0 (apt-get dist-upgrade) qtiplot запускается, но при наборе в две колонке цифр, их выделении и кликаньем по иконке "Plot as symbol" программа завершает работу. 

При запуске через gdb имеем:
$ gdb qtiplot
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This GDB was configured as "i586-alt-linux"...
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Using host libthread_db library "/lib/libthread_db.so.1".
(gdb) start
Function "main" not defined.
Make breakpoint pending on future shared library load? (y or [n])
Starting program: /usr/bin/qtiplot
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/usr/bin/qtiplot: Symbol `_ZTV9QwtSymbol' has different size in shared object, consider re-linking
/usr/bin/qtiplot: Symbol `_ZTV13QwtPlotPicker' has different size in shared object, consider re-linking
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[Thread debugging using libthread_db enabled]
[New process 10861]
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---Type <return> to continue, or q <return> to quit---
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[New Thread -1234643152 (LWP 10861)]
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Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread -1234643152 (LWP 10861)]
0xb7ec3a4c in QwtPlotGrid::enableY () from /usr/lib/libqwt.so.5
(gdb) kill

настараживают строки (см. выше)
"...
/usr/bin/qtiplot: Symbol `_ZTV9QwtSymbol' has different size in shared object, consider re-linking
/usr/bin/qtiplot: Symbol `_ZTV13QwtPlotPicker' has different size in shared object, consider re-linking
..."

похоже что переезд на новую версию библиотеки libqwt-5.1.1-alt1 вызвал сбои в работе программы. Ее явно надо пересобрать и слинковать с новой версией. И возможно принудительно прописать зависимости в спек.