calendar export (ics) of future passes

The format looks straightfoward to create a simplistic ICS file. That is one that is written and not intended to be updated or reissued by gpredict at tle's update or also updated from another machine.

Assumedly, these would go anyplace the print or view pass menus appear currently.

Is there a default place where calendaring files go under gnome or any other desktop environment? Home directory seems a safe default. If there is a standard though it would be nice to meet it. Later we can switch to whatever directory the user selects as is currently done with tle updates from file.

Are there any other expectations not addressed before coding starts?

(The difficulty for updating them is creating the event ID's in a way that TLE independent as pass start time, stop time and even orbit number can change with TLE for the "same" pass. If someone has an idea or trick for this, please advise. Maintaining a database of calendared passes works if we want one machine/user account to do the updates for passes it issued. However if say I originally schedule the pass using my home desktop and later want to update it with my laptop on the road, the database would need to be distributed which seems undesirable.)

When the user selects "Save" in the predicted passes window he/she can select which format to save in, see screenshot uploaded by submitter. Currently only plain text is supported, but other formats can be added. The user is asked where to save the file and the chosen location is remembered till the next time. Plain and simple.

As an FYI for debugging, there is a RFC 5545 (iCalendar) validator at
<http://icalvalid.cloudapp.net/>