Revision control
++ QT += widgets scxml
++ requires(qtConfig(combobox))
++
++ CONFIG += c++11
++
++ STATECHARTS = sudoku.scxml
++
++ SOURCES += \
++ main.cpp \
++ mainwindow.cpp
++
++ HEADERS += \
++ mainwindow.h
++
++ RESOURCES += \
++ sudoku.qrc
++
++ # install
++ target.path = $$[QT_INSTALL_EXAMPLES]/scxml/sudoku
++ INSTALLS += target