This problem was introduced when I recently updated to the current version.
If you load a device test plan and the test plan includes X-Y plots that open with it on a second monitor. Then when you reposition the Device Test Plan dialog box (Left click in the heading and drag), it also repositions all the X-Y plots as a group by the same offset. As if the plots were part of the Device Test Plan Dialog box. If you reposition individual X-Y plots there is no affect on the Test Plan Dialog box. Also if you minimize the Device Test Plan dialog box it minimizes the entire MI application, not just the Test Plan.