Will a function pointer be NULL by default?
<p>In the class below, would this mean that onPaintCallback is NULL, or must I make it NULL in the class constructor? I want to start checking for NULL before it is given a valid pointer.</p>

<pre><code>class AguiWidgetBase
{
    virtual void onPaint();
    void (*onPaintCallback)(AguiRectangle clientRect) = 0;
public:
    AguiWidgetBase(void);
    ~AguiWidgetBase(void);
};
</code></pre>
