Rerendering bug when a ListBox is associated to a DropdownBox

Question

As I was developing a UI that addressed a handful of related yet separate use cases, I came across a defect in the rerendering logic for ListBox (SAPUI5 library version 1.20.3 ).
(Working example here: http://jsbin.com/sidiq/1/edit?html,output )
When the UI is initially rendered, the associated ListBox would not be visible on screen, just the DropdownBox would be visible. Whenever I would alter the visibility state (in particular, making them visible) of elements it would cause the associated ListBox to suddenly appear.
It turns out the ListBox, on rerendering, is creating a second copy of itself in DOM. It's this second copy you're actually seeing on the screen. Once I figured that out I was able to hook the onAfterRendering event (via the Control.addDelegate() method) & query the DOM using the jQuery Attribute Equals Selector and remove the extra copy.
One nice byproduct is this gives a nice solution to situations where you want to want a control fully "rendered" as [HTML] DOM, but simply not displayed to the user. The solution employed by the event handler is to call jQuery .remove(), we could just as easily called .css("display", "none")
Those that prefer a gist can access it here: https://gist.github.com/scollenburg/5ec9ebc9cdae031c08c1
(or clone via git: https://gist.github.com/5ec9ebc9cdae031c08c1.git )
Enjoy,
Shawn
P.S. I'm working on filing this as a bug @ SAP, however that is going slowly, and I wanted to share the issue with everyone.

Answer 1

I was asked "why not bind the aggregation directly to the DropdownBox" -- this pattern (binding the aggregation to a ListBox, then associating the ListBox to one or more UI5 controls) comes directly from the SAPUI5 documentation:
Using a ListBox for the DropDownBox allows a reuse of this ListBox in multiple DropDownBoxes. This is useful for tables, for example, where the possible values are the same in every row.
The complete documentation can be found here:
SAPUI5 Demo Kit - DropdownBox -- Example 2: A DropdownBox Using a ListBox
Enjoy,
Shawn