Text Boxes

I've seen programs that can show you what is inside of a text box when you move the mouse over it.
This includes password boxes. How do they work?
I've did some research and all I could come up with is that,
When the mouse is moved over the box 'MSG' are passed to that window.
Then i'm guessing my program would get the handle to the window and box.
Is that how its done?

and if so how would I be able to look at all the messages that is system sends?

Read the post by (TNT) in this thread http://cprogramming.com/cboard/showt...threadid=15916 and it should help you out. Use the ChildWindowFromPoint() function.