Javascript Closure/Event Handling Nightmare

I am using the ovi maps API and I have a polyline with an event handler. The event handler looks like the following

 SomeClass = Base.extend({
    _clickFunction: function(evt) {
          alert(this.someBaseClassMethod() + 'x: ' + evt.targetX+ 'y:'+ evt.targetY);
    },
    go: function(){
          myClickableThing.addListener('click', this._clickFunction.bind(this));
    }
   }

The first time I click my thing I get X and Y that are correct for the pixel position of the cursor and an accurate timestamp. For every subsequent click on the same polyLine I get the exact same X,Y,and Timestamp. Does anyone have any thoughts or a workaround?

First off, thanks for all those that answered. I did manage to solve this problem although I can't tell you why it didn't work in the first place(If anyone regularly fishes around in the ECMAscript standard please feel free to contact me). The issue was definitely this._clickFunction.bind(this)). For what ever reason this creates a closure that retains the evt object. The solution(as some of you suggested in the comments) was simply to work around that line by setting the function up in the constructor.

Original:

   SomeClass = Base.extend({
    _clickFunction: function(evt) {
          alert(this.someBaseClassMethod() + 'x: ' + evt.targetX+ 'y:'+ evt.targetY);
    },
    go: function(){
          myClickableThing.addListener('click', this._clickFunction.bind(this));
    }
   }

Fixed Version:

  SomeClass = Base.extend({
    _clickFunction:null,
    constructor: function(){
      this._clickFunction = function(evt) {
          alert(this.someBaseClassMethod() + 'x: ' + evt.targetX+ 'y:'+ evt.targetY);
      }
    },
    go: function(){
          myClickableThing.addListener('click', this._clickFunction);
    }
   }