re-add Auto AR. Tie it to the desktop resolution which does not change when toggling between fullscreen and windowed. This assumes that the desktop resolution is using square pixels. This assumption will hold true for all out-of-the-box machines with a widescreen display.

stepmania/src/RageDisplay_D3D.cpp

@@ -314,6 +314,16 @@ void RageDisplay_D3D::GetDisplayResolutions( DisplayResolutions &out ) const
 	}
 }
 
+float RageDisplay_D3D::GetMonitorAspectRatio() const
+{
+#if defined(XBOX)
+	// FIXME
+	return 4/3.f;
+#else
+	return g_DesktopMode.Width / (float)g_DesktopMode.Height;
+#endif
+}
+
 D3DFORMAT FindBackBufferType(bool bWindowed, int iBPP)
 {
 	HRESULT hr;