From 44035f5ef17d30f4f383603dd299c89ff61889d6 Mon Sep 17 00:00:00 2001
From: Camilla Berglund <elmindreda@users.sourceforge.net>
Date: Sun, 8 May 2011 16:29:33 +0200
Subject: [PATCH] Added error check.

---
 src/opengl.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/opengl.c b/src/opengl.c
index 2e5e287d..7621b438 100644
--- a/src/opengl.c
+++ b/src/opengl.c
@@ -606,6 +606,12 @@ GLFWAPI void glfwCopyGLState(GLFWwindow hsrc, GLFWwindow hdst, unsigned long mas
     src = (_GLFWwindow*) hsrc;
     dst = (_GLFWwindow*) hdst;
 
+    if (_glfwLibrary.currentWindow == dst)
+    {
+        _glfwSetError(GLFW_INVALID_VALUE, "Cannot copy OpenGL state to a current context");
+        return;
+    }
+
     _glfwPlatformCopyGLState(src, dst, mask);
 }