No subject

// These are internal fltk symbols that are necessary or useful for
// calling Xlib.  You should include this file if (and ONLY if) you
// need to call Xlib directly.  These symbols may not exist on non-X
// systems.

There are macros further on that use XCreatePixmap in their definition:

#   define fl_create_offscreen(w,h) \
  XCreatePixmap(fl_display, \
              (Fl_Surface_Device::surface()->class_name() ==
Fl_Display_Device::class_id ? \
              fl_window : fl_xid(Fl::first_window()) ) , \
              w, h, fl_visual->depth)

So I'd say that fltk apps that use this header really do need to specify
-lX11 in their own LDFLAGS as they will need these symbols directly.

So it's an flrig bug.

It's easy to work around:

$ LDFLAGS="-lX11" ./configure && make
[...]
$ ldd src/flrig
	linux-vdso.so.1 =>  (0x00007fffccb82000)
	libX11.so.6 => /lib64/libX11.so.6 (0x0000003c77600000)
[...]

I couldn't see where to report bugs on w1hkj.com...

Regards,
Bryn.