I cannot do much for an explaination--it is just the way the graph works. I speculate that the cursor is part of the graph but it is treated separately. By mousing down and moving the cursor, the UI thread is locked by the cursor code. This prevents other events from firing like mouse move. If you would like to see the behavior changed, you can submit feedback to R&D. Goto www.ni.com >> contact ni (top bar)>> feedback.
