There's not "OnItemPostPaint", neither in Windows SDK (or MFC or other known library from MS), nor in WTL.
It just looks (with respect of some naming convention) like an application-defined message handler name.
So you cannot expect to find it in MSDN or WTL documentation.
Last edited by ovidiucucu; January 2nd, 2013 at 12:53 AM.
That code snippet handles a notification sent by a custom draw control.
Please, have a look in our previous discussion, and note again: in Windows there is no "standard" message/notification handler (name).
So generally, it has no much sense to search documentation for a given message/notification handler name. Instead, search for the message/notification name itself.
In our case: first search MSDN for NM_CUSTOMDRAW notification code, then dig into the related topics: