master branch: File Preview not working in Comments

I built a clean vtiger system for testing from the master branch a day or two ago.

The FilePreview function works OK in the Documents module, but not in ModComments. My guess it is to do with changing the file's stored name...

Also, why have two duplicate sets of code between the two modules? In Actions DownloadFile and in views FilePreview... These are quite useful methods for developers of custom modules too - why not move them into the main Vtiger class so there is only one set to maintain?