Drag and Drop Files from the VST plug-in to Local

Hi, as a starter of audio Programming, here I met some problem that I have no idea to tackle it, I need your inspiration~~~

When I use the ADD2 VST instrument, there is an impressing function that allows the user to drag the MIDI files stored somewhere on the disk and drop(copy) to the directory that targeted.
Here I paste the screenshot, hoping my description much more clear~

I’ve already built the fileTree with DragAndDropTarget, but seems the DragAndDropTarget is more likely to read the file from outside the application combined with DragAndDropContainer.

Does there any ideas on how to drop the selected file from FileTree to the path outside of the application?

And Thank you for your help~~~

Use DragAndDropContainer::performExternalDragDropOfFiles to drag file from your plugin to somewhere external (host DAW or general filesystem).

Thank you~~~~~ I will try~~