Today I just noticed that I wasn't able to post a comment using this plugin, it kept getting a JS error provided below (this was on the Rockmelt browser, similar to chrome):
jquery.min.js:4 Uncaught TypeError: Cannot read property 'style' of undefined
After further investigation, i noticed that the beginning of the function wpac_showMessage had
jQuery('#wpadminbar'), for me I turned this off so this element was not available therefore throwing the above error. What I did was changed
var top = wpac_options.popupMarginTop + jQuery("#wpadminbar").outerHeight();
if(jQuery('#wpadminbar').length > 0) var top = wpac_options.popupMarginTop + jQuery("#wpadminbar").outerHeight(); else var top = wpac_options.popupMarginTop;
and now it works fine. Just wanted to give you a heads up just in case other people were wondering about this error.