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	Don-vip	"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	closed	normal		JMapViewer		fixed	Mapnik, zoom, 19, download