Add xhandler hook
Boiler plate code to intercept system events from FLTK so that
we can generate proper keyboard messages.
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 30520a5..f5a016a 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -300,6 +300,9 @@
# FLTK STR #2860
check_cxx_source_compiles("#include <FL/Fl_Window.H>\nint main(int c, char** v) { void (Fl_Window::*foo)(int,int,int,int) = &Fl_Window::fullscreen_screens; return 0; }" HAVE_FLTK_FULLSCREEN_SCREENS)
+ # FLTK STR #xxxx
+ check_cxx_source_compiles("#include <FL/Fl.H>\nint main(int c, char** v) { Fl::add_xhandler(NULL, NULL); return 0; }" HAVE_FLTK_XHANDLERS)
+
set(CMAKE_REQUIRED_INCLUDES)
set(CMAKE_REQUIRED_LIBRARIES)
endif()