Sunday Afternoons: Slack Key Guitar Concerts. Traditional Hawaiian slack key guitar and `ukulele concerts. April 5 – Traditional Hawaiian Slack Key; April 12 – Hawai`i’s Sunset Music; April 19 – Legends of Slack Key; April 26 – Kaua`i’s Slack Key. Tickets: $20 ($15 keiki/seniors). The concerts are nahenahe - soft and sweet.  Slack key guitar and `ukulele in the real old style.  All traditional music with songs and stories of the islands, telling the history of this Hawaiian musical art form.…