We've created new freeware plugin to Quick.Cart v4.x.
Checks if the script includes all the bug fixes. If not then plugin will display status "Fix it!". Then You should fix it manually by clicking link "read more" and change all necessary files step by step.
You should know HTML to install this plugin.
WE STRONGLY RECOMMEND TO INSTALL THIS PLUGIN.
Check out this plugin here: http://opensolution.org/download,en,18.html?sDir=Quick.Cart/plugins#bugFixesChecker_v0.1