With the sun just right, “UMSL” reflects through the window onto the lobby floor of UMSL at Grand Center, the new home to St. Louis Public Radio | 90.7 KWMU. The public is invited to tour the building at an open house from 10 a.m. to 2 p.m. Sept. 15. Renee Montagne, co-host of NPR’s “Morning Edition,” will be on hand to greet visitors.