OSX refresh rate

refresh_rate_osx.diff

diff --git a/src/video/cocoa/cocoa_v.h b/src/video/cocoa/cocoa_v.h
index 371e4b5bc..3d3db5454 100644
--- a/src/video/cocoa/cocoa_v.h
+++ b/src/video/cocoa/cocoa_v.h
@@ -47,6 +47,8 @@ public:
 
 	void EditBoxLostFocus() override;
 
+	std::vector<int> GetListOfMonitorRefreshRates() override;
+
 	/* --- The following methods should be private, but can't be due to Obj-C limitations. --- */
 
 	void MainLoopReal();
diff --git a/src/video/cocoa/cocoa_v.mm b/src/video/cocoa/cocoa_v.mm
index 8d1fd4447..3f1dadbaf 100644
--- a/src/video/cocoa/cocoa_v.mm
+++ b/src/video/cocoa/cocoa_v.mm
@@ -228,6 +228,24 @@ void VideoDriver_Cocoa::EditBoxLostFocus()
 	HandleTextInput(nullptr, true);
 }
 
+/**
+ * Get refresh rate of the current screen.
+ */
+std::vector<int> VideoDriver_Cocoa::GetListOfMonitorRefreshRates()
+{
+	std::vector<int> rates{};
+
+	NSNumber *scr = [ [ [ this->window screen ] deviceDescription ] objectForKey:@"NSScreenNumber" ];
+	if (scr != nil && MacOSVersionIsAtLeast(10, 6, 0)) {
+		CGDisplayModeRef mode = CGDisplayCopyDisplayMode((CGDirectDisplayID)[ scr unsignedIntValue ]);
+		int rate = (int)CGDisplayModeGetRefreshRate(mode);
+		if (rate > 0) rates.push_back(rate);
+		CGDisplayModeRelease(mode);
+	}
+
+	return rates;
+}
+
 /**
  * Get the resolution of the main screen.
  */