This solves the issue where the parent dialog is closed and then
the child dialog is used.
This is however only a partial fix:
- Many other dialogs throughout the codebase do not currently have
parent windows and need to be refactored.
- Not all window managers respect modal so users can still trigger
bugs. We can be more defensive against this but it requires more
refactoring.
Closes#2686
- Fixes#314
- Adds file extensions to sound and image browsing
- Some options no longer default to our config dir
- Always add a shortcut to our config dir
- Remove broken 'last_dir' functionality, gtk already knows recent
