Besides upgrading to a more recent version of jQuery, there were some bugs fixed and some outdated information corrected. For details see the roadmap archive.

Update from 1.4.x to 1.4.5 

Upload the new files in the cmsimplexh folder over your existing 1.4.x installation, and change the setting of "autoload" in the configuration of the jQuery Plugin. As always we recommend making a backup of your website before updating.