I believe that when using MA, most people use the default directories (Images, Decks, ...) directly from the MA directory. It is especially useful if you use MA from your flash drive as it can mounted to a different disk character each time you plug in the drive. Absolute paths for these settings are not a way to go in most cases unless you install on a hard drive and need to use non-default directories...

By trial and error, I found out that relative paths actually work if used.

This FR is to add these relative paths as default values to MA preferences, i.e. add "Images (Pictures)", "Decks" and "Inventory" to each respective field.
The default directory for images is not currently shipped through updater, might be a good idea to add it.

Default filter that would come with MA is probably unnecessary.

Also, a "Restore to defaults" button to the Preferences dialog might be useful to reset your settings.