How can dragover target determine an OLE dragdrop's source?

I would like my OLEdragdrop DragOver code determine the source of an OLE dragdrop operation so it can examine the source control for content. By source I mean the control that initiated the dragdrop operation currently underway. I recognize that this may not always be a control in my application.

I think I can use the oDataObject.SetData() to store a handle to the source object but I'm concerned that this technique may leave a dangling handle in certain scenarios (error conditions, etc). Or I could set (in a manual OLE dragdrop initiated method) and clear a global application property that references the current OLE dragdrop source.

Is there a better way to generically determine the source of an OLE dragdrop operation? I've tried ThisForm.ActiveControl and _Screen.ActiveForm.ActiveControl but both these values do not contain an object reference when an OLE dragdrop operation is underway?

Malcolm