How can I maximize a window across multiple monitors?

Using AutoHotkey, How can I bind a hotkey to stretch/maximize/span a window across multiple monitors so that it covers both displays?

Right now, I have to do this by manually stretching the windows with the mouse. I know there are dedicated tools that do this, but I'm already running an AutoHotkey script and would rather limit the number of tools I keep running.

Here's how I did it, mapping the Shift + Windows + Up combination to maximize a window across all displays. This compliments Windows 7's Windows + Up hotkey, which maximizes the selected window.

AHK v1

+#Up::
    WinGetActiveTitle, Title
    WinRestore, %Title%
   SysGet, X1, 76
   SysGet, Y1, 77
   SysGet, Width, 78
   SysGet, Height, 79
   WinMove, %Title%,, X1, Y1, Width, Height
return

AHK v2

+#Up::
{
    Title := WinGetTitle("A")
    WinRestore(Title)
    X1 := SysGet(76)
    Y1 := SysGet(77)
    Width := SysGet(78)
    Height := SysGet(79)
    WinMove(X1, Y1, Width, Height, Title)
}