Is there any documented way to filter dragged data?

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VC6

C++

COM

I have hooked DoDragDrop in explorer.exe using IAT hooking mathod. it works(my proxy function is called whenever a user drags any selected object in windows explorer). than after unhooking it, draging any selected object crashes explorer.exe.

My purpose behind hooking DoDragDrop is
To get IDataObject created by explorer.exe.
To read it.
To generate new IDataObject based on content in the IDataObject received in my proxy function.
and To call the original DoDragDrop with newly generated IDataObject.
( thus I filter out files dragged and dropped by user from Windows explorer to any application )

I have achieved my purpose through IAT hooking but it is not reliable.

Is there any documented way to fulfill my purpose?

Thanks in advance.