If I write a function that will be called both from the Main Thread and from child threads (created using fl_create_thread()), will it be a problem for the Main Thread if there are calls to Fl::lock() and Fl::unlock() in it?
That is, can I call Fl::lock() from the Main Thread, with an equivalent number of Fl::unlock() calls, and not compromise my thread safety?

If I should not call Fl::lock() from the Main Thread, then is there a way to determine if a thread is the Main Thread or not??

Thanks, any info appreciated!

Ah, answered my own questions:

1. The Fl::lock() is "recursive" which means it can be called from the main thread as long as the same piece of code does an equivalent number of FL::unlock() calls before returning to the FLTK main loop.

2. You can find out if you are the main thread by calling fltk::in_main_thread(). This call must be protected by calls to Fl::lock and Fl::unlock.

Happy Threading!!!

ps- now that I have been playing with multi-threaded fltk i have quickly found that the FLTK provided threading doesn't give you much. I recommend using pthreads to get the added functionality in a cross-platform way.