Layer order changing when turning layer on/off

Question

I have two geoJson layers being loaded - both layers are the same data for testing purposes, but being drawn from two different json files. When I turn the layers on and off in the layer controller, the draw order of the layers change.

Any ideas why this is happening?

I have put my code into a JSFiddle: http://jsfiddle.net/lprashad/ph5y9/10/ and the JS is below:

//styling for watersheds_copy
var Orange = {
    "color": "#ff7800",
        "weight": 5,
        "opacity": 0.65
};

var Water_Orange = L.geoJson(watersheds_copy, {
    style: Orange
});

Water_Orange.addData(watersheds_copy);

//these are blue
var Water_blue = L.geoJson(watersheds, {});
Water_blue.addData(watersheds);

//This sets the inital order - last in layer list being on top. Except minimal   - tile layer is always on bottom
var map = L.map('map', {
    center: [41.609, -74.028],
    zoom: 8,
    layers: [minimal, Water_Orange, Water_blue]
});

var baseLayers = {
    "Minimal": minimal,
        "Night View": midnight
};

//This controls the order in the layer switcher. This does not change draw order
var overlays = {
    "Water_Orange": Water_Orange,
        "Water_blue": Water_blue
};
L.control.layers(baseLayers, overlays).addTo(map);

LP

Answer 1

While searching I happened upon this site that shows some of the Leaflet code: http://ruby-doc.org/gems/docs/l/leaflet-js-0.7.0.3/lib/leaflet/src/control/Control_Layers_js.html

In it I found this condition for the application of autoZIndex:

    if (this.options.autoZIndex && layer.setZIndex) {
            this._lastZIndex++;
            layer.setZIndex(this._lastZIndex);
    }

TileLayer is the only layer type that has a setZIndex function, so apparently autoZIndex only works there.

I'm not sure which annoys me more. This incredible limitation or the fact that Leafet documentation doesn't point it out.