DESCRIPTION:
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In a dialog window the user can select the layers should be visible in the TOC


CONFIGURATION:
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The following configuration settings are needed:

config_default.xml:
under <pluginsConfig> add a block like

    <layerselect>
        <categories>
            <category name="cat_admin">
                <group>countries</group>
                <group>admins</group>
                <group>cities10000eu</group>
                <group>urban</group>
            </category>
            <category name="cat_nature">
                <group>rivers</group>
                <group>corine</group>
                <group>water</group>
            </category>
            <category name="cat_infrastructure">
                <group>roads</group>
                <group>railroad</group>
            </category>
            <category name="cat_raster">
                <group>dem</group>
                <group>jpl_wms_global_mosaic</group>
            </category>
        </categories>
    </layerselect>
    
These are all possible layers a user can select. The layers defined under
<map><allGroups> must be a subset or all of these layers.

Opening the dialog is performed via a tool link, toolbar button or whatever control
someone would like to use. It has to call the JavaScript method
    PM.Plugin.Layerselect.openDlg

an entry for the toolLink config PM.linksDefault in js_config.php would be e.g.
    {linkid:'layerselect', name:'Select Layers', run:'PM.Plugin.Layerselect.openDlg', imgsrc:'layers-bw.png'}