eGroupware Customization - Upload Progress Bar

The customization is adding an Upload Progress Bar to the FileManager module in eGroupware. Upon completion you will submit the code to the eGroupware project for inclusion. The code must be clean and integrate well with the eGroupware's structures. This is for the latest version of eGroupware (1.4). Please indicate what technologies or existing packages you plan to use - pear, ajax, etc.. Please provide any experience you have developing for eGroupware.