When Lois Mailou Jones began painting in the 1920s, she did so in near anonymity, a sign of the endemic racism and sexism of the time. But 92 years after her first exhibition, Ms. Jones is now the focus of a new exhibit at the Martha’s Vineyard Museum, running from June 12 to August 23 this summer. Nearly 17 years after she died, Ms. Jones is once again on display in the Vineyard.