make setVisibility() actually call display(). also add some comments on this rather funky situation.

git-svn-id: http://svn.openlayers.org/trunk/openlayers@1615 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Layer.js

@@ -236,7 +236,15 @@ OpenLayers.Layer.prototype = {
         return this.visibility;
     },
 
-    /** 
+    /** Set the visibility flag for the layer and hide/show&redraw accordingly. 
+     *   Fire event unless otherwise specified
+     * 
+     * Note that visibility is no longer simply whether or not the layer's
+     *  style.display is set to "block". Now we store a 'visibility' state 
+     *  property on the layer class, this allows us to remember whether or not
+     *  we *desire* for a layer to be visible. In the case where the map's 
+     *  resolution is out of the layer's range, this desire may be subverted.
+     *  
      * @param {Boolean} visible Whether or not to display the layer 
      *                          (if in range)
      * @param {Boolean} noEvent
@@ -244,6 +252,7 @@ OpenLayers.Layer.prototype = {
     setVisibility: function(visibility, noEvent) {
         if (visibility != this.visibility) {
             this.visibility = visibility;
+            this.display(visibility);
             if (this.map != null) {
                 var extent = this.map.getExtent();
                 if (extent != null) {
@@ -257,7 +266,8 @@ OpenLayers.Layer.prototype = {
         }
     },
 
-    /** 
+    /** Hide or show the Layer
+     * 
      * @param {Boolean} display
      */
     display: function(display) {