drag_data_delete

Asks the TreeDragSource to delete the row at path, because it was moved somewhere else via drag-and-drop.

Returns false if the deletion fails because path no longer exists, or for some model-specific reason. Should robustly handle a path no longer found in the model!

Parameters:

this	a TreeDragSource
path	row that was being dragged

Returns:

true if the row was successfully deleted