Does any fellow developer know why the FLTK threading doc states :

"Don't intermix use of Fl::awake(Fl_Awake_Handler cb, void* userdata) and Fl::awake(void* message) calls in the same program as they may interact unpredictably on some platforms" ?

Do these platforms include Linux?

I'm asking because I'm exploring the use of Posix timers to implement Fl::add_timeout() 

for the Wayland platform (see the timer_create() and timer_settime() functions).

These functions allow to trigger the timer either as a signal or starting a thread.
I've chosen the thread option, and have the thread call Fl::awake(cb, data)

so that the timer's callback gets then called by the main thread in its event loop.

This solution works nicely in my tests, but has Fl::awake(cb, data) called by the library

when the app calls Fl::add_timeout(). Thus, a user of both Fl::add_timer()

and Fl::awake(void*) may find herself to intermix both forms of Fl::awake()

without knowing it if that solution is used to implement Wayland timers.