get_clipboard_string() is broken

[installgentoo]

If you call get_clipboard_string() while you clipboard is empty, on linux at least, you'll panic on

    if (!*selectionString)
    {
        _glfwInputError(GLFW_FORMAT_UNAVAILABLE,
                        "X11: Failed to convert selection to string");
    }

and one needs to provide error callback to avoid this. Meanwhile get_clipboard_string() returns Option<> so you expect it to just return None instead of panicking.

[aloucks]

I agree that it's a little surprising, but this is the expected outcome if you use glfw::init(glfw::FAIL_ON_ERRORS). Perhaps you could submit a GLFW issue to treat an empty clipboard differently from conversion error.

As you mentioned, providing a custom error callback could be used to ignore GLFW_FORMAT_UNAVAILABLE. It wouldn't hurt to add some documentation to this method to describe this edge case.