"View Source" open the file in its default application that is associated with that file name extension. File association associates a file with an application capable of opening that file.
May be you are trying to view a file whose type (extension) is not recognized by your operating system. Assign the application you want to use to open that file first and then do the view source.
When I click on view source in TS GUI under Actions tab, after selecting a file, I get a message "there is no file association for the file file_name, do you want to add one " When I click on yes, some screen blinks and this message is gone. Again when I select same file and clik on the view source, I again get the same message. what does this message mean ? whats file association ? Pls explain