I use ZenPhoto version 1.4.1 because it runs well on Windows Server 2008.
If you use the paypal plugin from http://zenphoto.dev.stephane-huc.net/pages/ZenPaypal-Plugin you may like to add a "view cart" button.
In text editor open
plugins/ZenPayPal/class.zenPayPal.php
After line 472 add:
///add view cart button
$html .= '<p><form target="paypal" action="https://www.paypal.com/cgi-bin/webscr" method="post">
<input type="hidden" name="business" value="YOURID@YOURDOMAINNAME.EXT">
<input type="hidden" name="cmd" value="_cart">
<input type="hidden" name="display" value="1">
<input type="image" name="submit" border="0" src="https://www.paypal.com/en_US/i/btn/btn_viewcart_LG.gif" alt="PayPal - The safer, easier
way to pay online">
<img alt="" border="0" width="1" height="1" src="https://www.paypal.com/en_US/i/scr/pixel.gif" >
</form></p>'."\n";
///end add view cart button
Be SURE to replace YOURID@YOURDOMAINNAME.EXT with YOUR Paypal ID!