'Home Screen: Feature not support' is not related to mobility sensor use.
You cannot install Qt4.7.3 on Belle (111.010.1009) because you cannot point Qt version dependency in SmartInstaller it is done automatically.
To explore your device environment (even in Remote Device service) you can use QInfo utility available in binary installer form from http://projects.developer.nokia.com/qtinfo project.
I re-checked accelerometer test with N700 , Firmware: 111.010.1009
On that test i refer many times during that conversation thread and the point is in problem analysis we need first to localize the problem and accelerometer test proves your problem is not related to Mobility sensors at all.
Here is my device environment dump from QInfo utility:
I do not observe 'Home Screen: Feature not support'. Please let me know what else API your app employs. Do you use home widget?
Below you can see the details of your current Qt installation.
Qt version 4.7.4
Qt build Fri Aug 19 2011, Symbian full-config, Open Source
Language English (en_GB)
Qt modules QtCore QtDeclarative QtGui QtMultimedia phonon QtNetwork QtOpenGL QtOpenVG QtScript QtSql QtSvg QtTest QtWebKit QtXmlPatterns QtXml QtBearer QtConnectivity QtContacts QtFeedback QtGallery QtLocation QtMultimediaKit QtSensors QtServiceFramework QtSystemInfo QtOrganizer QtPublishSubscribe QtVersitOrganizer QtVersit
OS / Firmware 5.3 / 111.010.1009
Screen (0) 360x640, 32b
Library path C:/Private/a00002d6
Plugin path \resource\qt\plugins
Import path \resource\qt\imports
Image formats bmp, gif, ico, jpeg, jpg, mng, pbm, pgm, png, ppm, svg, svgz, tif, tiff, xbm, xpm
Hardware features Bluetooth, Camera, Memory card, USB, Vibra, WiFi, SIM, GPS, Haptics
Sensors QTapSensor, QMagnetometer, QOrientationSensor, QAmbientLightSensor, QAccelerometer, QProximitySensor, QCompass, QRotationSensor