Nothing special here. To tie it in with some ExtJS effects we need to get at its inners using the ColdFusion.Window.getWindowObject() function. In the example below once we get the window object we add a listener to it using the shorthand ExtJs notation of "on" to look for when the mouse enters and leaves the window. When the mouse enters we log to the console the id of the element (it can be useful to know the id of it) and then perform a highlight effect on the windowContent div. When the mouse leaves we hide the window.
Thats it! ExtJs has a bunch of cool effects that can be applied to an element.
Here's a short screencast showing the code above in action: