I have removed the line that was suggested but I still get an Abort trap:

port-39:rtv-Stage-cf05051 juniobranco$ stage worlds/simple.world
Stage 4.0.0 
stage(52690,0x7fff7009dca0) malloc: *** error for object 0x101024a08: incorrect checksum for freed object - object was probably modified after being freed.
*** set a breakpoint in malloc_error_break to debug
Abort trap

Thank you for your quick reply.

> Try removing 
>set_target_properties( stagebinary PROPERTIES LINK_FLAGS "${FLTK_LDFLAGS}" )

>from libstage/CMakeLists.txt and recompiling.