PASS GUI initial controls
PASS GUI multi-file drop handler adds four worlds
PASS GUI duplicate source not added
PASS GUI asynchronous four-world analysis
PASS GUI End selection from fourth world
PASS GUI bulk third source preserves exclusive fourth-source player
PASS GUI missing source cannot be selected
PASS GUI compact tables and all bulk sources
PASS GUI busy controls protect source list
PASS GUI removal invalidates old selections
PASS GUI reanalysis renumbers sources correctly
