Mac OS X does not need glFlush() called, swapping the buffers does it implicitly.

stepmania/src/RageDisplay_OGL.cpp

@@ -27,6 +27,10 @@ using namespace RageDisplay_OGL_Helpers;
 #pragma comment(lib, "glu32.lib")
 #endif
 
+#ifdef NO_GL_FLUSH
+#define glFlush()
+#endif
+
 //
 // Globals
 //

stepmania/src/arch/LowLevelWindow/LowLevelWindow_MacOSX.mm

@@ -271,7 +271,6 @@ void RenderTarget_MacOSX::StartRenderingTo()
 void RenderTarget_MacOSX::FinishRenderingTo()
 {
 	DEBUG_ASSERT( m_OldContext );
-	glFlush();
 	glBindTexture( GL_TEXTURE_2D, m_iTexHandle );
 	
 	while( glGetError() != GL_NO_ERROR )

stepmania/src/archutils/Darwin/arch_setup.h

@@ -23,6 +23,8 @@ extern "C" int SM_main( int argc, char *argv[] );
 #define CRASH_HANDLER
 
 #define GL_GET_ERROR_IS_SLOW
+// CGFlushDrawable() performs a glFlush() and the docs say not to call glFlush()
+#define NO_GL_FLUSH
 
 #if defined(__ppc__)
 # define CPU_PPC