Article ID: 98678
Article Last Modified on 3/3/2005
APPLIES TO
- Microsoft OLE 2.0
- Microsoft OLE 4.0, when used with:
- Microsoft Windows NT 4.0
- Microsoft Windows NT 3.51 Service Pack 5
- Microsoft Windows NT 4.0
- Microsoft Windows 95
- Microsoft Windows 2000 Standard Edition
This article was previously published under Q98678
OLE (object linking and embedding) version 2.0 container applications should never call QueryInterface to get a pointer to the IOleInPlaceActiveObject interface. Instead, the container should AddRef() the pointer passed to IOleInPlaceUIWindow::SetActiveObject and save it until needed.
Consider the scenario in which a nested object is currently inplace active; that is, the container contains an object and this contained object in turn holds another object that is inplace active. The container has a pointer only to the "outer" object, and is not aware of the "inner" object. Calling QueryInterface to get a pointer to IOleInPlaceActiveObject is meaningless on the outer object because the outer object is not currently inplace active. The only reliable way to get a pointer to the correct IOleInPlaceActiveObject interface is through IOleInPlaceUIWindow::SetActiveObject.
Objects capable of inplace activation should guard against this case, and never return IOleInPlaceActiveObject from QueryInterface.
Additional query words: 2.00 3.50 4.00
Keywords: kbinplaceact KB98678
