g++ -c -pipe -O2 -Wall -W -D_REENTRANT -DQT_NO_DEBUG -DQT_GUI_LIB -DQT_CORE_LIB-DQT_SHARED -I/usr/share/qt4/mkspecs/linux-g++ -I. -I/usr/include/qt4/QtCore -Iusr/include/qt4/QtGui -I/usr/include/qt4 -I. -I. -o mainwindow.o mainwindow.cpp
mainwindow.cpp: In destructor ‘virtual MyWidget::~MyWidget()’:
mainwindow.cpp:19: error: ‘w2’ was not declared in this scope
In file included from mainwindow.cpp:4:
/usr/include/qt4/QtGui/qwidget.h: In copy constructor ‘My2_Widget::My2_Widget(cnst My2_Widget&)’:
/usr/include/qt4/QtGui/qwidget.h:782: error: ‘QWidget::QWidget(const QWidget&)’is private
zweitwindow.h:12: error: within this context
mainwindow.cpp: In member function ‘void MyWidget::TuWas()’:
mainwindow.cpp:25: note: synthesized method ‘My2_Widget::My2_Widget(const My2_Wdget&)’ first required here 
mainwindow.cpp:26: error: base operand of ‘->’ has non-pointer type ‘My2_Widget
make: *** [mainwindow.o] Fehler 1