I tried in win7 two times, strictly step by step, by your instructions. From Step1 to Step9, all is OK. But when I start a new app, the same error appeared. I tried again as follow:
First, I start Qtcreator, and open the qtitanribbon.pro by Step1, Step2,...,Step9. Eveything is all right. After running qmake(Step7), No errors. And after running Build All, No errors. Then, I pressed Ctrl+R, and the "Qtitan Ribbon Backstage Sample" window appeared. See pic110.jpg
Second, I created a Qt Widgets Application in QtCreator. I added "include(C:/Qt/QtitanRibbon/src/shared/qtitanribbon.pri)" in the .pro file. Then, I run qmake from the menu, and run Build All from the menu. I pressed Ctrl+R, and the platform and qtitanribbon file appeared in the new app project at left of view. So far, No errors.
Third, I added "include <QtitanRibbon.h>" in main.cpp. The the same error appeared again.
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Then I added QTITANDIR variable(QTITANDIR=C:\Qt\QtitanRibbon\) to the environment(Step6) in this project. Run qmake, No errors. Run Build All, No errors. Then, Ctrl+R, a new error appeared:This application failedto start because it could not find or load the Qt platform plugin "windows". See pic111.jpg
Then, I pressed ENTER, the following error appeared. See pic112.jpg.