How to get overlapping rectangle coordinates
<p>Assume I have the following overlapping rectangles ("a" and "b"):</p>

<pre><code>aaaaaaaa
aaaaccccbbbbb
aaaaccccbbbbb
aaaaccccbbbbb
    bbbbbbbbb
    bbbbbbbbb
</code></pre>

<p>I've seen lots of ideas on how to calculate the <em>area</em> of the inner rectangle ("c"), but how would I go about getting the actual top/left/bottom/right coordinates for it?</p>
