Hello,
both libraries (RunTime Environment and Graphis Engine) have no dependencies to any operating system. So, changing the underlying operating system within the provided Build Environment should be pretty straight forward. Just search all *.h and *.c files for the define EW_USE_FREE_RTOS and implement the corresponding OS III functionality.
Due to the fact that Embedded Wizard contains its own heap manager, you just need to provide a memory area. There is no need to adapt the memory alloc/free functions.
Please take care to reserve enough stack for the GUI task (4...8 kByte).
If there are still errors, please check also the console window.
Btw: Which version of Embedded Wizard are you using and which target are you using?
Best regards,
Manfred.