1)If you want to write plug-in, then you need to make specially COM dll, with CoClass that implement IDTExtensibility2 and (I seems) IDTCommandTarget and some else 2)You can write application that automate Office, use Ole automation. Try to see #import directive help some interesting you may find http://www.codeproject.com/com/xoffice.asp[^]

You can handle WM_ERASEBKGND message

Try to use CDocTemlate class for this purposes, OpenDocumentFile member. You must register DocTemplate first! Another way is to use CWinApp::OpenDocumentFile or AfxGetApp()->OpenDocumentFile instead.