Hi Todd Millett,
I am sorry for the delayed reply,
Following your description I tried to recreate your scenario but it worked as expected on my side. I am attaching the project that I created to test this.
The problem that you describe comes from the fact the CheckBox (and all other buttons) capture the mouse on MouseDown. We listen to the mouse events of the row but this does not work since the check box has captured the events from then on.
Since this does not seem like an issue in my project, probably I am missing something. Could you have a look at it and modify it so that it breaks or, alternatively, modify your implementation so that it works similarly.
Normally we should handle cases like this one, so I will be happy to patch the RadDragDrop to avoid acting unexpectedly.
All the best,
the Telerik team