According to the MSDN docs on the WM_PRINT message, here's what happens when a WM_PRINT message is received and processed by the DefWindowProc function:
The DefWindowProc function processes this message based on which drawing option is specified: if PRF_CHECKVISIBLE is specified and the window is not visible, do nothing, if PRF_NONCLIENT is specified, draw the nonclient area in the specified device context, if PRF_ERASEBKGND is specified, send the window a WM_ERASEBKGND message, if PRF_PRINTCLIENT is specified, send the window a WM_PRINTCLIENT message, if PRF_PRINTCHILDREN is set, send each visible child window a WM_PRINT message, if PRF_OWNED is set, send each visible owned window a WM_PRINT message.
If I want to do custom drawing of the background or the client area, I can respond properly to the WM_ERASEBKGD and WM_PRINTCLIENT messages, but what about custom rendering of the non-client area? What message can I override/process to handle that? WM_NCPAINT is *not* called. Is there something else that is that I can hook into and add my custom NC drawing code?