Dragging services fails intermittently

I can dupe both on uistage and locally with improv. Dupe instructions will be for local + improv, with notes on the one difference I see in uistage.

In the environment view, click and drag a service. This will be our first service drag, of two.
For the purposes of comparison with subsequent behavior, described below, drag this service around for about 10 or 15 seconds, to verify that the drag continues to work.
Release the mouse button from the first drag. *On local/improv, the notifications icon in the top right will briefly turn from red to orange. You must perform the next step before the notifications icon becomes red again in order to dupe the problem. On uistage, I do not see the change to orange, and you seem to have a longer window in which to trigger the problematic behavior.*
Immediately click and drag a second service. For the purposes of the second part of this story, it should have a relation line to another service, but I do not believe that is necessary for the actual problem described in this story.
Do not release the mouse button from the second drag. Instead, for the next 10 to 15 seconds, continue to drag.

WHAT SHOULD HAPPEN: you can continue to drag the service around for the entire time.
WHAT DOES HAPPEN: the service stops following your mouse, even though you have not released the mouse button.

There is further problematic behavior, but I suspect that this is what Ben is working on for bug 1083917, so I will describe it, but I think it is a separate issue that Ben will address as part of his work. Continuing the story above...

You have not yet released the mouse button from the second drag. Move the mouse to a location, and release the mouse button. Do not move the mouse further, and wait 10 or 15 seconds.

WHAT SHOULD HAPPEN: Nothing.
WHAT SHOULD HAPPEN IF A DELTA STREAM UPDATES A SERVICE LOCATION: Once Ben commits a fix for bug 1083917, the service moves over to the new location.
WHAT DOES HAPPEN: The relation line connecting to the second service points approximately to where your mouse is, as if the service were there. The service actually stays where it was before.

Again, I don't think we should work on this in isolation. We should fix the first part of this story, and let Ben fix bug 1083917.

I suspect that the failed drag happens because of the new annotation storage of the x,y location of the first service. I further suspect that this is a problem for any delta stream change--that is, I suspect that any delta stream change will cause an in-progress drag to fail. Just a hunch.