Don't do anything if sorter was replaced, even for one tick only. Hopefully fixes
issue #907, but not confirmed, though very highly plausible.
# -------------------------------------------------
# Project created by QtCreator 2010-11-27T22:18:20
# -------------------------------------------------
TARGET = drawMapTest
TEMPLATE = app
SOURCES += main.cpp \
mainwindow.cpp \
drawmapscene.cpp \
qaspectratiolayout.cpp \
drawmapwidget.cpp
HEADERS += mainwindow.h \
drawmapscene.h \
qaspectratiolayout.h \
drawmapwidget.h
FORMS += mainwindow.ui