Feature : ofPresentWindow()

Hey!

I use a feature quite often, where I force glfw to present the window "as is" (e.g. during an update)
generally this involves something like:

glfwSwapBuffers(glfwGetCurrentContext());
glFlush();

This has been relatively stable with OpenGL 2 on Windows and OSX. I had to fiddle a bit when we moved to 0.9.0 (not sure why), but now I've moved Rulr to OpenGL 3.2, I'm having issues again.

For a start, glfwGetCurrentContext now returns NULL (great! how did that happen? :)
But even if I do something like

            auto window = ofGetWindowPtr();
            auto glfwAppWindow = dynamic_cast<ofAppGLFWWindow*>(window);
            if (glfwAppWindow) {
                auto glfwWindow = glfwAppWindow->getGLFWWindow();
                ofClear(0, 0);
                drawText(message, 0, 0, true, ofGetHeight(), ofGetWidth());
                glfwMakeContextCurrent(glfwWindow);
                glfwSwapBuffers(glfwWindow);
                glfwPollEvents();
            }

I still don't get the drawing on the screen.
The next frame of the app works fine, but i never see that drawText happen.

I use this feature especially for scanning, where it's important to sync the timing of the drawing and capture, and when using a for loop is much easier than sending the graphics out on separate app frames.

I'm wondering:

1. What am I doing wrong this time?
2. Could we make this a core feature? (especially as changes to oF core seem to break this usage)

Start by tracing the provided glfwSwapBuffers, glfwMakeContextCurrent, and glfwPollEvents calls through ofAppGLFWWindow, using ofGetWindowPtr() and getGLFWWindow() as entry points. Reproduce the missing immediate drawing with the supplied loop, then define and verify a core API that presents the current window reliably during such a loop.