id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc
9031	Increase max zoom for Mapnik in download window	Felis Pimeja	team	"Increase max zoom for Mapnik tiles from 17 to 19 in download window, as it's now available on OpenStreetMap.org

Maybe it'somewhere here:

https://trac.openstreetmap.org/browser/subversion/applications/viewer/jmapviewer/src/org/openstreetmap/gui/jmapviewer/tilesources/OsmTileSource.java"	enhancement	new	normal		Core			Mapnik, zoom, 19, download