In my case :
- Activate STemWin in CubeMX
- Generate Code
- In properties of the project
- C/C++ General -> Path and Symbols
- In library Paths add : Middlewares/ST/STemWin/Lib/
- In Libraries add :STemWin_CM7_OS_wc32_ot_ARGB.a
DONE
STM32
TrueStudio
CubeMX
STemWin