Thanks for getting back to me. In my case I’m trying to override the showing of .png, jpg, jpeg, and .gif files with icons rather than previews. I found that if I removed the content from the array that holds those file types I do indeed get the icons.
Also, within the package file list display, I would like to show a filetype icon beside each item. In our case we are providing the same file in up to 6 different formats and it would be nice to have a visual indicator of the file type to make it easier to quickly see which file the client needs to download for the purpose they need it.