Examples: OpenGL: Fix for OSX not supporting OpenGL 4.5, we don't try to read GL_CLIP_ORIGIN even if the OpenGL headers/loader happens to define the value. (#2366, #2186)

docs/CHANGELOG.txt

@@ -38,6 +38,8 @@ Other Changes:
 - InputInt, InputFloat, InputScalar: Fix to keep the label of the +/- buttons centered when
   style.FramePadding.x is abnormally larger than style.FramePadding.y. Since the buttons are
   meant to be square (to align with e.g. color button) we always use FramePadding.y. (#2367)
+- Examples: OpenGL: Fix for OSX not supporting OpenGL 4.5, we don't try to read GL_CLIP_ORIGIN
+  even if the OpenGL headers/loader happens to define the value. (#2366, #2186)
 
 
 -----------------------------------------------------------------------

examples/imgui_impl_opengl3.cpp

@@ -11,10 +11,11 @@
 
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
+//  2019-02-20: OpenGL: Fix for OSX not supporting OpenGL 4.5, we don't try to read GL_CLIP_ORIGIN even if defined by the headers/loader.
 //  2019-02-11: OpenGL: Projecting clipping rectangles correctly using draw_data->FramebufferScale to allow multi-viewports for retina display.
 //  2019-02-01: OpenGL: Using GLSL 410 shaders for any version over 410 (e.g. 430, 450).
 //  2018-11-30: Misc: Setting up io.BackendRendererName so it can be displayed in the About Window.
-//  2018-11-13: OpenGL: Support for GL 4.5's glClipControl(GL_UPPER_LEFT).
+//  2018-11-13: OpenGL: Support for GL 4.5's glClipControl(GL_UPPER_LEFT) / GL_CLIP_ORIGIN.
 //  2018-08-29: OpenGL: Added support for more OpenGL loaders: glew and glad, with comments indicative that any loader can be used.
 //  2018-08-09: OpenGL: Default to OpenGL ES 3 on iOS and Android. GLSL version default to "#version 300 ES".
 //  2018-07-30: OpenGL: Support for GLSL 300 ES and 410 core. Fixes for Emscripten compilation.
@@ -169,7 +170,7 @@ void    ImGui_ImplOpenGL3_RenderDrawData(ImDrawData* draw_data)
     GLboolean last_enable_depth_test = glIsEnabled(GL_DEPTH_TEST);
     GLboolean last_enable_scissor_test = glIsEnabled(GL_SCISSOR_TEST);
     bool clip_origin_lower_left = true;
-#ifdef GL_CLIP_ORIGIN
+#if defined(GL_CLIP_ORIGIN) && !defined(__APPLE__)
     GLenum last_clip_origin = 0; glGetIntegerv(GL_CLIP_ORIGIN, (GLint*)&last_clip_origin); // Support for GL 4.5's glClipControl(GL_UPPER_LEFT)
     if (last_clip_origin == GL_UPPER_LEFT)
         clip_origin_lower_left = false;