Cannot call OpenCV 2.0 functions inside Qt slots

[Asfer]

Hi all,

I have a Qt (4.6 mingw) application that uses OpenCV (2.0) for image processing.

Everything was working fine with OpenCV 1.0 but when I upgraded to
OpenCV 2.0 it started crashing.
I noticed that it only crashes whenever OpenCV functions are called
inside Qt slots.

For instance, the following slot:

void TestClass::on_testButton_clicked() {
   IplImage* src = cvLoadImage("test.jpg");
   IplImage* dst = cvCreateImage(cvGetSize(src), src->depth, src->nChannels);
   cvThreshold(src, dst, 100, 255, CV_THRESH_BINARY);
}

void TestClass::on_testButton_clicked() {
   IplImage* src = cvLoadImage("test.jpg");
   IplImage* dst = cvCreateImage(cvGetSize(src), src->depth, src->nChannels);
   cvThreshold(src, dst, 100, 255, CV_THRESH_BINARY);
}

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crashes when testButton is clicked.

However:
If I call the same cvThreshold function in any other place such as main or the Widget's constructor, it works.
If f I put the same code in a separate function and call that function with QtConcurrent::run() inside the same slot, it works.
If I use OpenCV 1.0, it works.

Why this behaviour? Are there any restrictions about the operations that can be done inside Qt slots?

Thanks in advance.