title: What is the use of the ui.qml files in Qt5 (QML)?
body: <p>As far as I can see the .qml files can be used to define the UI, which seems to override whatever is written in ui.qml file.
  So, what exactly is the use of the ui.qml file?</p>
  
  <p>I'm using Qt5 with Qt Creator.</p>