Better documentation for the property ImgPath of OpenLayers.

lib/OpenLayers.js

@@ -83,9 +83,38 @@
         
         /**
          * APIProperty: ImgPath
-         * {String} Set this to the path where control images are stored.
-         *          If set to '' OpenLayers will use script location + "img/"
-         *          Default is ''.
+         * {String} 
+         * 
+         * Set this to the path where control images are stored, a path given 
+         * here must end with a slash. If set to '' (which is the default) 
+         * OpenLayers will use its script location + "img/".
+         * 
+         * You will need to set this property when you have a singlefile build of 
+         * OpenLayers that either is not named "OpenLayers.js" or if you move
+         * the file in a way such that the image directory cannot be derived from 
+         * the script location.
+         * 
+         * If your custom OpenLayers build is named "my-custom-ol.js" and the images
+         * of OpenLayers are in a folder "/resources/external/images/ol" a correct
+         * way of including OpenLayers in your HTML would be:
+         * 
+         * (code)
+         *   <script src="/path/to/my-custom-ol.js" type="text/javascript"></script>
+         *   <script type="text/javascript">
+         *      // tell OpenLayers where the control images are
+         *      // remember the trailing slash
+         *      OpenLayers.ImgPath = "/resources/external/images/ol/";
+         *   </script>
+         * (end code)
+         * 
+         * Please remember that when your OpenLayers script is not named 
+         * "OpenLayers.js" you will have to make sure that the default theme is 
+         * loaded into the page by including an appropriate &lt;link&gt;-tag, 
+         * e.g.:
+         * 
+         * (code)
+         *   <link rel="stylesheet" href="/path/to/default/style.css"  type="text/css">
+         * (end code)
          */
         ImgPath : ''
     };