Events before drop a file

[wf-soft]

'''
DataObject fileDrop = new DataObject(DataFormats.FileDrop, files.ToArray());
DragDrop.AddQueryContinueDragHandler(Helper.Main.ViewEx, DocItem_QueryContinueDrag);
DragDrop.DoDragDrop(Helper.Main.ViewEx, fileDrop, DragDropEffects.All);
'''

I want to implement the ability of querycontinuedraghandler when files are placed in the resource manager or other programs, but it seems that dropped can not be hit. Is there any other way to decide whether to drop before drop