--- VirtualBox-5.1.24/src/VBox/HostServices/SharedOpenGL/render/renderspu_glx.c.orig	2017-07-19 10:39:46.904477445 -0400
+++ VirtualBox-5.1.24/src/VBox/HostServices/SharedOpenGL/render/renderspu_glx.c.orig	2017-07-19 10:40:02.987383444 -0400
@@ -1924,8 +1924,6 @@ 
     }
 }
 
-#define CR_RENDER_FORCE_PRESENT_MAIN_THREAD
-
 void renderspu_SystemVBoxPresentComposition( WindowInfo *window, const struct VBOXVR_SCR_COMPOSITOR_ENTRY *pChangedEntry )
 {
     /* the CR_RENDER_FORCE_PRESENT_MAIN_THREAD is actually inherited from cocoa backend impl,