Revision control
++ HEADERS = connection.h \
++ imageitem.h \
++ informationwindow.h \
++ view.h
++ RESOURCES = drilldown.qrc
++ SOURCES = imageitem.cpp \
++ informationwindow.cpp \
++ main.cpp \
++ view.cpp
++ QT += sql widgets
++ requires(qtConfig(combobox))
++
++ # install
++ target.path = $$[QT_INSTALL_EXAMPLES]/sql/drilldown
++ INSTALLS += target