Of the three functions for opening a window, only OpenWindow() is present in all versions of the OS. This function takes a NewWindow structure as its sole argument. In order to allow applications to use the OpenWindow() call with Release 2 TagItem attributes, an extended version of the NewWindow structure has been created named ExtNewWindow. Setting WFLG_NW_EXTENDED in the NewWindow.Flags field specifies to the OpenWindow() call that this NewWindow structure is really an ExtNewWindow structure. This is simply a standard NewWindow structure with a pointer to a tag list at the end. Since WFLG_NW_EXTENDED is ignored prior to V36, information provided in the tag list will be ignored by earlier versions of Intuition. Note that WFLG_NW_EXTENDED may not be specified in the WA_Flags tag.
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