1. Open the attached project and configure it to use Qt 4.8.
2. Place the cursor in the call to

   tc.write();
   

   in main.cpp and trigger "Find Usages".
   Creator will find three usages in C++, but not the usage in QML.

3. Place the cursor in the call to

   tc.write();
   

   in main.qml and trigger "Find Usages".
   Creator will find a usage in QML, but not the usages in C++.

I think "Find Usages" should find all usages of a function, regardless where it is being used. Features like "Follow Symbol Under Cursor" should work for a C++ function, even when the cursor is at a call in a QML file.
Use case? I nearly deleted a seemingly unused function from Creator. Would have broken the Welcome mode...