On Wednesday 29 January 2020 05:23:18 pm Dave Lers wrote: Hi Dave, That's actually the exact steps I used to start this whole thing. I did find out later that isn’t really the preferred way, as then it becomes hard to find the change later. The seemingly recommend way is to go into File Associations and add the extension to the existing group/item it fits under. Using wanting to edit DOS batch files as the example (e.g. add .bat to text/plain) : TCC >> TDE Components >> File Associations In “Known Types” Click ‘text’ Click ‘plain’ In “Filename Patterns” Click ‘Add...’ Type ‘*.bat’ Click OK Click ‘Add...’ Type ‘*.BAT’ Click OK Like most of *nix there’s more than one way to do it, so the .bat extension could have also been added to something like application/kwrite. I’d probably prefer this last method, but my system (stock MX18/TDE) doesn’t have anything like application/kwrite. User mime types are stored in ~/.trinity/share/mimelnk . Running find doesn’t find anything there either: # find * -type f -iname "*kw*" application/x-kword.desktop # find * -type f -iname "*tde*" # find * -type f -iname "*kons*" application/x-konsole.desktop # Konsole exists, but I’d guess TDE never updated mime types to TDE naming, nor probably has done anything with the defaults?