Added simple context sharing test program.
diff --git a/tests/sharing.c b/tests/sharing.c
new file mode 100644
index 0000000..765b4ec
--- /dev/null
+++ b/tests/sharing.c
@@ -0,0 +1,144 @@
+//========================================================================
+// Context sharing test program
+// Copyright (c) Camilla Berglund <elmindreda@elmindreda.org>
+//
+// This software is provided 'as-is', without any express or implied
+// warranty. In no event will the authors be held liable for any damages
+// arising from the use of this software.
+//
+// Permission is granted to anyone to use this software for any purpose,
+// including commercial applications, and to alter it and redistribute it
+// freely, subject to the following restrictions:
+//
+// 1. The origin of this software must not be misrepresented; you must not
+// claim that you wrote the original software. If you use this software
+// in a product, an acknowledgment in the product documentation would
+// be appreciated but is not required.
+//
+// 2. Altered source versions must be plainly marked as such, and must not
+// be misrepresented as being the original software.
+//
+// 3. This notice may not be removed or altered from any source
+// distribution.
+//
+//========================================================================
+//
+// This program is used to test sharing of objects between contexts
+//
+//========================================================================
+
+#include <GL/glfw3.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+
+static GLFWwindow open_window(const char* title, GLFWwindow share)
+{
+ GLFWwindow window;
+
+ window = glfwOpenWindow(400, 400, GLFW_WINDOWED, title, share);
+ if (!window)
+ return NULL;
+
+ glfwSwapInterval(1);
+
+ return window;
+}
+
+static GLuint create_texture(void)
+{
+ int x, y;
+ char pixels[256 * 256];
+ GLuint texture;
+
+ glGenTextures(1, &texture);
+ glBindTexture(GL_TEXTURE_2D, texture);
+
+ for (y = 0; y < 256; y++)
+ {
+ for (x = 0; x < 256; x++)
+ pixels[y * 256 + x] = rand() % 256;
+ }
+
+ glTexImage2D(GL_TEXTURE_2D, 0, GL_LUMINANCE, 256, 256, 0, GL_LUMINANCE, GL_UNSIGNED_BYTE, pixels);
+ glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+ glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+
+ return texture;
+}
+
+static void draw_quad(GLuint texture)
+{
+ glMatrixMode(GL_PROJECTION);
+ glLoadIdentity();
+ gluOrtho2D(0.f, 1.f, 0.f, 1.f);
+
+ glEnable(GL_TEXTURE_2D);
+ glBindTexture(GL_TEXTURE_2D, texture);
+ glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);
+
+ glColor3f(0.6f, 0.f, 0.6f);
+
+ glBegin(GL_QUADS);
+
+ glTexCoord2f(0.f, 0.f);
+ glVertex2f(0.f, 0.f);
+
+ glTexCoord2f(1.f, 0.f);
+ glVertex2f(1.f, 0.f);
+
+ glTexCoord2f(1.f, 1.f);
+ glVertex2f(1.f, 1.f);
+
+ glTexCoord2f(0.f, 1.f);
+ glVertex2f(0.f, 1.f);
+
+ glEnd();
+}
+
+int main(int argc, char** argv)
+{
+ GLFWwindow windows[2];
+ GLuint texture;
+
+ if (!glfwInit())
+ {
+ fprintf(stderr, "Failed to initialize GLFW: %s\n", glfwErrorString(glfwGetError()));
+ exit(EXIT_FAILURE);
+ }
+
+ windows[0] = open_window("First", NULL);
+ if (!windows[0])
+ {
+ fprintf(stderr, "Failed to open first GLFW window: %s\n", glfwErrorString(glfwGetError()));
+ exit(EXIT_FAILURE);
+ }
+
+ texture = create_texture();
+
+ windows[1] = open_window("Second", windows[0]);
+ if (!windows[1])
+ {
+ fprintf(stderr, "Failed to open second GLFW window: %s\n", glfwErrorString(glfwGetError()));
+ exit(EXIT_FAILURE);
+ }
+
+ while (glfwIsWindow(windows[0]) && glfwIsWindow(windows[1]))
+ {
+ glfwMakeWindowCurrent(windows[0]);
+ glClear(GL_COLOR_BUFFER_BIT);
+ draw_quad(texture);
+ glfwSwapBuffers();
+
+ glfwMakeWindowCurrent(windows[1]);
+ glClear(GL_COLOR_BUFFER_BIT);
+ draw_quad(texture);
+ glfwSwapBuffers();
+
+ glfwWaitEvents();
+ }
+
+ glfwTerminate();
+ exit(EXIT_SUCCESS);
+}
+
