#42 "Show All" disabled when arcs are filtered

[Rob Lintern]

**** Small Warning Bells ****
Problem: Show All Button in the Arc filter is disabled
when arcs are filtered.

Possible Solution: It's not immediately obvious a group
has to be selected. Select the Default Group by
default. New users will understand, and medium users
will figure out how to create groups.

Possible Solution2: Can the buttons be put on the
groups? The buttons are only associated with the group
item, and not an arc. It doesn't make sense to have
them where they seem to affect all items.