[Win] Log wglSwapIntervalEXT errors

Note that we cannot use Marshal.GetLastWin32Error because we are not
using regular DllImports for WGL extensions.

diff --git a/Source/OpenTK/Platform/Windows/WinGLContext.cs b/Source/OpenTK/Platform/Windows/WinGLContext.cs
index 74a5009..b7da272 100644 (file)
--- a/Source/OpenTK/Platform/Windows/WinGLContext.cs
+++ b/Source/OpenTK/Platform/Windows/WinGLContext.cs
@@ -331,7 +331,10 @@ namespace OpenTK.Platform.Windows
                         {
                             value = 1;
                         }
-                        Wgl.Ext.SwapInterval(value);
+                        if (!Wgl.Ext.SwapInterval(value))
+                        {
+                            Debug.Print("wglSwapIntervalEXT call failed.");
+                        }
                     }
                 }
             }