>As for SendMessage(), there isn't event that actually gets fired, the message just gets send directly to the application's window procedure, and the application decides what to do with the message. In most cases you're limited to the stock Windows messages (you can send a custom message, but that doesn't mean the receiving application knows what to do with it), so this may or may not work for you. There are examples for using SendMessage() in the FAQ if this is what you need. What specifically are you trying to accomplish?
I'd amplify this statement to say that SendMessage() and PostMessage() and their related API cousins actually queue up indicators (messages) of event occurances in the thread or Window event queue; they don't 'trigger' an event, but act as indicators of an event having taken place, in some cases carrying additional information related to the event (ie, a WM_KEYDOWN message indicates to the event loop that a key was depressed, and it carries additional information indicating exactly which virtual key was pressed.)
Making the sassumption that a SendMessage() 'causes' an event to fire is a pretty clear indication that the person doesn't understand what a Windows message is in the first place - time to read Petzold or Richter and figure this stuff out before blindly setting off little landmines whith unknown effects.