Thunar 1.8.14 - change drag and drop behaviour

I've just noticed that Thunar on my pc COPIES files when they are dragged and dropped into another folder, rather than MOVING them.

There is another answer to this question saying Thunar can MOVE files by dragging and dropping with the right mouse button. But I'd be grateful to know if it's possible to change the behaviour for dragging and dropping with the left mouse button from COPY to MOVE?

thanks, Catty