I am trying to categorize the behavior of the automatic priority boost done by windows in certain scenarios. I can see a +1 priority boost for around 200 ms when doing a Wait on a Semaphore or Mutex. I expected that a similar boost would occur when a message is received by a window, because that thread must be blocking on a wait somewhere, right? But when I test this out by sending a WM_USER message (and verify that I receive that message on the window thread), there is no priority boost. Can anyone explain why?

Here is the MSDN link about the priority boost:

http://msdn2.microsoft.com/en-us/library/ms684828.aspx

Thanks