Zoom To MaxExtent and OpenLayers.Control.ZoomToMaxExtent

HTML

<script src="http://cdnjs.cloudflare.com/ajax/libs/openlayers/2.12/OpenLayers.js"></script>
<link rel="stylesheet" href="http://cdnjs.cloudflare.com/ajax/libs/openlayers/2.12/theme/default/style.css">
<link rel="stylesheet" href="http://dev.openlayers.org/releases/OpenLayers-2.13.1/examples/style.css">
<body onload="init()">Zoom in and then Click on the world-icon to zoom back To Max-Extent
    <br />
    <div id="map" class="smallmap"></div> <a href="javascript:map.zoomToMaxExtent();">Zoom To Max Extent (click!)</a>

</body>
<br />
<p>see also <a href="http://gis.stackexchange.com/questions/23836/openlayers-zooming-and-panning-restrictions-dont-work">http://gis.stackexchange.com/questions/23836/openlayers-zooming-and-panning-restrictions-dont-work</a>

</p>

CSS

.olControlPanel {
    position:absolute;
    left:50px;
}
.olControlPanel div {
    display:block;
    width: 24px;
    height: 24px;
    margin: 5px;
    background-color:white;
}
.olControlPanel .olControlZoomToMaxExtentItemInactive {
    width: 18px;
    height: 18px;
    background-image: url("http://dev.openlayers.org/releases/OpenLayers-2.13/img/zoom-world-mini.png");
}

JavaScript

var map;

function init() {

    var layer = new OpenLayers.Layer.OSM(
        "OpenStreet Maps", null, {
        resolutions: [19567.87923828125, 9783.939619140625,
        4891.9698095703125, 2445.9849047851562, 1222.9924523925781,
        611.4962261962891, 305.74811309814453, 152.87405654907226,
        76.43702827453613, 38.218514137268066, 19.109257068634033,
        9.554628534317017, 4.777314267158508, 2.388657133579254,
        1.194328566789627, 0.5971642833948135, 0.29858214169740677,
        0.14929107084870338, 0.07464553542435169],
        serverResolutions: [156543.03390625, 78271.516953125,
        39135.7584765625, 19567.87923828125, 9783.939619140625,
        4891.9698095703125, 2445.9849047851562, 1222.9924523925781,
        611.4962261962891, 305.74811309814453, 152.87405654907226,
        76.43702827453613, 38.218514137268066, 19.109257068634033,
        9.554628534317017, 4.777314267158508, 2.388657133579254,
        1.194328566789627, 0.5971642833948135, 0.29858214169740677,
        0.14929107084870338, 0.07464553542435169]
    });

    var extent = [-1500000, 4000000, 5600000, 11000000];

    map = new OpenLayers.Map('map', {
        projection: 'EPSG:3857',
        //maxExtent: extent,
        //restrictedExtent: extent,
        layers: [layer]
    });
    map.addControl(new OpenLayers.Control.LayerSwitcher());

    var panel = new OpenLayers.Control.Panel();
    panel.addControls([
    new OpenLayers.Control.ZoomToMaxExtent({
        title: "Zoom to the max extent"
    })]);
    map.addControl(panel);


    map.zoomToMaxExtent();


}