I wanted to load each tab's content whenever it is displayed, and not load it until then.  That way, the page loads much faster.

Doing so is fairly easy, and let's you do the following:

<div class="tab-pane" id="tabPane1">
  <div class="tab-page" id="tabPage1" onshow="alert('Load away!');">
  </div>
</div>

The onshow event is triggered when the page first loads, and whenever the tab is selected.

Simply change the WebFXTabPage.prototype.show function on line 243 in tabpane.js to this:

WebFXTabPage.prototype.show = function () {
   var el = this.tab;
   var s = el.className + " selected";
   s = s.replace(/ +/g, " ");
   el.className = s;

   this.element.style.display = "block";

   // add this code below
   this.onshow = this.element.getAttribute("onshow");
   if (this.onshow == "" || this.onshow == null) return;
   if (typeof this.onshow == "string")
      this.onshow = new Function("event", this.onshow);
   this.onshow(window.event);
};