Steps to reproduce:
 - put a chart on content pane
 - make sure you have axis elected
 - try to drag axis outside the chart and drop there. SB does not allow you to drop inside chart but it does allow you to drop axis outside chart (there are alignment hints displayed, etc...).
This should not be allowed. Right now when you drop axis outside the chart it's drag 'view' stays on the content pane until you click mouse twice.