Note that WM_TIMER messages never result in an asynchronous call back. The message loop must be running and the 'queued' WM_TIMER message must be processed during the normal message loop polling for the call back function to be called. Also note that WM_TIMER messages are about the lowest of the low and will not get processed if there are any higher priority messages queued.

None if this may be relevant to the topic under discussion, but is somewhat non-obvious and can be critical information in some circumstances (say he who has been bit in the past)!