Hi, To add to @kshegunov, you might be interested by the Extending Qt Applications part of the Plugin HowTo in Qt's documentation.

@Duino said: I just meet a bug ghost in my code.That means if I try to find what happen inside,the code runs well.But if I don't, bugs happen. It's not a ghost. It's a Heisenbug :) How should I catch this bug ghost??? Simplify your program, do unit testing. and use a tool like Valgrind.