From Tracker Software PDF SDK
Called by the document to notify the handler that it is set as a selection handler for document's selection.
HRESULT OnStartSelHandling([in] IPXV_Document* pDoc, [in] IPXV_DocSelection* pNewDocSel);
- [in] Pointer to IPXV_Document containing the source document.
- [in] Pointer to IPXV_DocSelection containing the new document's selection.
Returns S_OK if operation was successful or error code in other cases.