Code to open a link in popup window using iframe on mouse click:
<iframe src="http://stackoverflow.com/" name="iframe_a">
<p>Your browser does not support iframes.</p>
</iframe>
<a href="http://melbourne.breakthroughacademy.com.au/" target="iframe_a"><img src="http://www.breakthroughacademy.net.au/wp-content/uploads/2014/05/register_btn.png" alt="button" class="alignnone size-medium wp-image-480" width="282" height="55" /></a> <a href="/#!about-us/"><img src="http://www.breakthroughacademy.net.au/wp-content/uploads/2014/05/i_symbol1.png" style="padding:0 0 0 10px;position:relative;top:-13px"/></a>