Forgot to mention, I haven't tried to send a password into the prompt yet because I completely forgot
I was just testing with two non-password accounts but I just tried it with a password and it worked.
That would seem to imply you are in the right place.
Damnit I wish I had time to play with this (office has me pinned to the wall).
Using GetDesktopWindow() I seem to get a consistant handle of 0x00010004, (IIRC), for the Welcome screen, now if I could only work out how to get the icon objects on it....
Of course, using the Classic logon would probably be a lot easier, just needing to send a load of key codes...but, naturally, my friend would rather use the Welcome screen
UPDATE: OK, bearing in mind I'm just playing in a VM and are stuck with 4:3 modes, the Welcome screen user icons are remarkably consistent in their positioning, (only tested up to 3 users so far).
The centre of the icons are located 60 pixels right of the screen centre and have a horizontal spacing of ~80 pixels, this is from resolution 800x600 -> 1280x960.
So given the location of the first icon, (using a simple lookup table), the position of those below can be calculated fairly easily.
Given the target is a two user system, this is pretty much solved only needing to be tested with wide screen modes to see if the spacing is significantly different.
In all cases the handle for the screen is 0x00010004, if I knew which process was responsible for placing of the icons it might be possible to make it a bit more intelligent. I thought it was logonui.exe but I can't seem to get the GUI resources it might be using.