This reminds me, where are file type associations stored? When I install an app and click on a file used by that app in File Manager, the app starts and opens the file. When I uninstall said app and later click on such a file, File Manager gives me a list of apps to select from to open the file with. So clearly the associations are kept somewhere the (un)install process can access. How can I change the association if I change my mind? That might be an answer to the OP's needs too. Just associate GIF with MicroB and job done...