Index: /trunk/src/VBox/Frontends/VirtualBox/src/platform/darwin/UICocoaDockIconPreview.mm
===================================================================
--- /trunk/src/VBox/Frontends/VirtualBox/src/platform/darwin/UICocoaDockIconPreview.mm	(revision 85330)
+++ /trunk/src/VBox/Frontends/VirtualBox/src/platform/darwin/UICocoaDockIconPreview.mm	(revision 85331)
@@ -160,5 +160,9 @@
 {
     NSImage *dockMonitor = ::darwinToNSImageRef(p->m_dockMonitor);
+#if MAC_OS_X_VERSION_MIN_REQUIRED >= MAC_OS_X_VERSION_10_12
+    [dockMonitor drawInRect:NSRectFromCGRect(p->flipRect(p->m_monitorRect)) fromRect:aRect operation:NSCompositingOperationSourceOver fraction:1.0];
+#else
     [dockMonitor drawInRect:NSRectFromCGRect(p->flipRect(p->m_monitorRect)) fromRect:aRect operation:NSCompositeSourceOver fraction:1.0];
+#endif
     [dockMonitor release];
 }