//String xy = ((Main.mousex - centerx) / 40) + Local.Self.mx + "," + ((Main.mousey - centery) / 40) + Local.Self.my;
if (Local.TilesByPos.containsKey(xy)) {
Tile t = marked = Local.TilesByPos.get(xy);
marker.position(t.onscreenx(), t.onscreeny(), marker.w(), marker.h());
} else {
marked = null;
marker.position(-40, -40, marker.w(), marker.h());
}
}