Leaflet/Leaflet — pull request #1683 by jfirebaugh (2013-05-15 20:51:06+00:00)
Title: tile layers added after initial load don't show up until zoomed

http://bl.ocks.org/jfirebaugh/abe9676ef9ce9165bfba

Zoom in, and the other two tile layers are shown.

In the initial state, the base layer has z-index 2 and the other layers have no explicit z-index, so they are below the base layer.