MainForm::MainForm( QWidget * parent, const char * name ) : QWidget( parent, name ){ secondForm = new SecondForm( this ); connect( secondForm, SIGNAL( changeConst( QInt ) ), this, SIGNAL( addConst( QInt ) ) );}...SecondForm::SecondForm( QWidget * parent, const char * name ) : QWidget( parent, name ){ connect( myBytton, SIGNAL( clicked() ), this, SLOT( myButtonClicked() ) ); ...}void SecondForm::myButtonClicked(){ QInt i = 2; emit changeConst( i );}