made OGL context more robust

glfw/glow-extras/glfw/GlfwApp.cc

@@ -461,8 +461,16 @@ void GlfwApp::endRender()
 {
     // draw the tweak bar(s)
     if (mDrawTweakbars)
+    {
         TwDraw();
 
+        // unbind TweakBar stuff
+        glActiveTexture(GL_TEXTURE0);
+        glBindTexture(GL_TEXTURE_2D, 0);
+        glUseProgram(0);
+        glBindVertexArray(0);
+    }
+
     // Swap front and back buffers
     glfwSwapBuffers(mWindow);
 }
@@ -568,6 +576,9 @@ int GlfwApp::run(int argc, char *argv[])
     TwWindowSize(mWindowWidth, mWindowHeight);
     mTweakbar = TwNewBar("Tweakbar");
 
+    // unbind any ogl object (especially from AntTweakBar)
+    glow::unbindOpenGLObjects();
+
     // input callbacks
     {
         glfwSetKeyCallback(mWindow, [](GLFWwindow *win, int key, int scancode, int action, int mods) {