====== QtWidgets/QApplication: No such file or directory ======
When compiling project using QT4.8:
<code>
fatal error: QtWidgets/QApplication: No such file or directory
 #include <QtWidgets/QApplication>
</code>

Wrong include in file (for QT5)
Should be 
<file | main.cpp>
 #include <QApplication>
</file>
<file | main.pro>
TEMPLATE += app
QT += gui declarative
SOURCES += main.cpp
</file>


====== libQt5OpenGL.so.5: cannot open shared object file ======
<code>
Got keys from plugin meta data ("gstreamermediaplayer")
QFactoryLoader::QFactoryLoader() checking directory path "/usr/bin/mediaservice" ...
loaded library "/usr/lib/qt/plugins/mediaservice/libgstmediaplayer.so"
QLibraryPrivate::loadPlugin failed on "/usr/lib/qt/plugins/mediaservice/libgstmediaplayer.so" : "Cannot load library /usr/lib/qt/plugins/mediaservice/libgstmediaplayer.so: (libQt5OpenGL.so.5: cannot open shared object file: No such file or directory)"
defaultServiceProvider::requestService(): no service found for - "org.qt-project.qt.mediaplayer"
</code>