commit 9a799da70ad9eef231660fff3ef040a57ef8250b
Author:     ManoloFLTK <41016272+ManoloFLTK@users.noreply.github.com>
AuthorDate: Wed Aug 26 22:01:09 2020 +0200
Commit:     ManoloFLTK <41016272+ManoloFLTK@users.noreply.github.com>
CommitDate: Wed Aug 26 22:01:09 2020 +0200

    Fix cmake-based build under macOS with OPTION_APPLE_X11.
    
    cmake now correctly finds GLU support when present.

 CMake/options.cmake | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git CMake/options.cmake CMake/options.cmake
index 3ea045e..e7eac47 100644
--- CMake/options.cmake
+++ CMake/options.cmake
@@ -74,9 +74,9 @@ if ((NOT APPLE OR OPTION_APPLE_X11) AND NOT WIN32)
 endif ((NOT APPLE OR OPTION_APPLE_X11) AND NOT WIN32)
 
 if (OPTION_APPLE_X11)
-  if (${CMAKE_SYSTEM_VERSION} VERSION_GREATER 16.9.0)
+  if (${CMAKE_SYSTEM_VERSION} VERSION_GREATER_EQUAL 17.0.0) # a.k.a. macOS version â?¥ 10.13
     list (APPEND FLTK_CFLAGS "-D_LIBCPP_HAS_THREAD_API_PTHREAD")
-  endif (${CMAKE_SYSTEM_VERSION} VERSION_GREATER 16.9.0)
+  endif (${CMAKE_SYSTEM_VERSION} VERSION_GREATER_EQUAL 17.0.0)
   include_directories (AFTER SYSTEM /opt/X11/include/freetype2)
   if (PATH_TO_XLIBS)
     set (LDFLAGS "-L${PATH_TO_XLIBS} ${LDFLAGS}")
@@ -193,7 +193,8 @@ if (OPTION_USE_GL)
   if (OPTION_APPLE_X11)
     set (OPENGL_FOUND TRUE)
     set (OPENGL_LIBRARIES -L${PATH_TO_XLIBS} -lGLU -lGL)
-    find_file (HAVE_GL_GLU_H GL/glu.h PATHS /opt/X11/include)
+    find_file (TEMP_HAVE_GL_GLU_H GL/glu.h PATHS /opt/X11/include)
+    set (HAVE_GL_GLU_H ${TEMP_HAVE_GL_GLU_H})
   elseif (OPTION_APPLE_SDL)
     set (OPENGL_FOUND FALSE)
   else()