VST vs. AU behaviour using DragAndDropContainer::performExternalDragDropOfFiles

I have a mouseDown() function for a component.  In there I call DragAndDropContainer::performExternalDragDropOfFiles. 

On PC VST and Mac AU it works fine.  I get a single call to the mouse function and the drag works as expected. 

However - on the Mac using VST after the drag is complete the plugin still seems to be in 'drag' mode.  No matter where on the plugin I click it calls the mouseDown() function again and tries to start another drag. 

I can't work out Juce is suppose to find out that the drag has finished, or the mouse button has been lifted outside of Juce (??) and I suppose clear some flag somewhere down in MouseInputSource ... 

I'm still digging around trying to understand what goes on under the hood, but any pointers would greatly appreciated!  

IIRC, that's supposed to be handled by OSX once the drag has begun, I don't think there's anything that the app has to do to make it work..

It only seems to be a problem when the drag target is the host (Ableton and Reaper exhibit the same behaviour).  If I drag to the desktop, or even Skype, then the drag appears to finish normally. 

I can detect when it's happened using something like:

void MyComponent::mouseDrag(mouseevent) { 

if (!getLocalBounds().contains(mouseevent.getPosition())) do_something_to_reset_the_situation;



But it's a bit of a hack, and it's not obvious what the do_something ought to be.