In Ubuntu, when we right-click a icon and use "open with", there is an option to remember that application for that file's type. For some reason, my system is no more memorizing the application (I think it was aftare some update). And, even when I have already used the "open with" command, the application is not showing in the "open with" list, so I have, everytime, to go to "open with"->"Other Application". The system used to ask me what to do with the file type (Display, Run..), but now it is doing nothing to my file type "ppf". I want it to open with GEdit. Is there any command line to associate my extension with GEdit? Answer Found, after unmark "Allow executing file as a program" it worked.. I don't know why this box was marked anyway..