Simple, in order for your class to use the event, you will need to declare the QT resizeEvent handler in the constructor, like below.
class Test : public QWidget
/** construtor */
Test(QWidget* parent=0, const char *name=0);
/** destructor */
then, you'll need to define the event handler's function like below...
void Test::resizeEvent(QResizeEvent *e)
So, whenever you resize the Test window, it will automatically be resized back to 100,100!