Three exhibitions featuring longtime coastal Marin residents, Pasty Krebs of Inverness and Sean Thackery and Harriet Kossman of Bolinas, open at the Bolinas Museum on April 7. Two of the exhibitions explore quiet nuances of color and light, while the third bursts with diverse textures and mediums. In the main gallery, “Focus: Patsy Krebs” presents the work of a . . .