Selenium.prototype.doClickAt = function(locator, coordString) {
    /**
   * Clicks on a link, button, checkbox or radio button. If the click action
   * causes a new page to load (like a link usually does), call
   * waitForPageToLoad.
   *
   * @param locator an element locator
   * @param coordString specifies the x,y position (i.e. - 10,20) of the mouse
   *      event relative to the element returned by the locator.
   *
   */
    var element = this.browserbot.findElement(locator);
    var clientXY = getClientXY(element, coordString)
    this.doMouseMove(locator);
    this.doMouseDown(locator);
    this.browserbot.clickElement(element, clientXY[0], clientXY[1]);
    this.doMouseUp(locator);
};