Hi, I ran into following issue when using CSplitterWindow in WTL10 7336 atlsplit.h(1101): error C2065: 'StartWindowProc': undeclared identifier and it goes away after I turned off /permissive- and looks like it came from DECLARE_WND_CLASS_EX. I found this post https://sourceforge.net/p/wtl/discussion/374433/thread/4e2dcc68/?limit=25#14fa, which sounds like this issue was fixed before WTL10 was released. Any idea why I'm still getting it? Oscar