Shoutbox

There is no handle: it's not a frigging window! I know: I've delved deeper into Messenger than most, trying to work out how it's constructed so I can exploit that to my own benign ends. SO, when I say there's no frigging handle to the PSM, there's no frigging handle!
Anyway, only developers will skills like Patchou are able to hook Winsock: I know, I've tried it myself and failed. And I'm no novice. And, you can intercept WMs and then work out which one is the PSM: it's not hard using Spy++. If there's a WM associated with a PSM change, it'll be caught by Spy++. Then it's a case of a simple subclass and filter function.

I suggest you go away and do some research into the Messenger window structure, then come back and read this thread and the one at Fanatic.