Requirements for a modern game engine

Text-based JSON data files - for everything possible
Comprehensive error-detection in API functions
Avoid callbacks
Fast in-engine update-on-demand for data changes
Procedural as much as possible
Physics-based rendering
Effects files (fx)

To link properly with the FBX SDK, define FBXSDK_SHARED in C++ preprocessor options.

Always replace Qt's sqlite code with the latest sqlite. Switching from Qt's 3.7 to 3.8.2 makes a 60-second query take 1/2 second.

In Qt, the sizePolicy for containers should be Expanding. That's the only policy that respects the minimum sizes of its contents. The policy "MinimumExpanding" ignores the contents and only looks at the widget's own minimum size value.