[OpenLayers-Users] Using custom Feature class

[nick@hogweed.org]

Following on from my experiments with tiled markers, it seems that the Feature 
class is designed to combine markers and popups in one, which is what I need.

So I have changed my code slightly to create a new class inherited from 
Feature.
What I want to do is make the popup associated with the feature appear when 
the user clicks on it. The event works (an alert box in the event handler 
appears) but I run into problems when trying to display the popup.

My feature class (nick.dev.openstreetmap.org/openlayers/osmfeature.js) is as 
follows:

OpenLayers.Feature.OSMtest = Class.create();
OpenLayers.Feature.OSMtest.prototype =
    Object.extend (new OpenLayers.Feature(), {

        thePopup: null,
        currentObj : null,

        initialize: function (layer,lonLat,data) {
            OpenLayers.Feature.prototype.initialize.apply(this,arguments);
            this.createMarker();
            this.thePopup = this.createPopup();

	    // this works
            if(this.thePopup)
                alert('popup created successfully');

            this.layer.addMarker(this.marker);
            this.marker.events.register('click',  this.marker,
                                this.showPopup);
            currentObj = this;

        },

        destroy: function() {
            if (this.marker != null) {
                this.layer.removeMarker(this.marker);
            }
            OpenLayers.Feature.prototype.destroy.apply(this,arguments);
        },

        showPopup: function() {
            alert('feature was clicked!');  // this works
            //this.thePopup.draw();
            currentObj.thePopup.draw();
        }

Note that I have added the 'currentObj' as I ran into 'no properties' errors 
with 'this.thePopup.draw()'. I figured this might be a scoping problem with 
'this' again (as a result of the 'onclick' call?) so I used 'currentObj' as 
an alternative reference for 'this'.
However now I get an error:

Error: this.map has no properties
Source File: http://openlayers.org/api/OpenLayers.js
Line: 359

As well as the error, another question.... am I going about this the right 
way, or is there a cleaner, automated way to associate features with popups, 
so that the popup associated with the feature automatically comes up when you 
click on the feature's marker?

Thanks,
Nick