; LetUserSelectRect by Lexikos
; 2009, http://www.autohotkey.com/forum/viewtopic.php?t=49784
LetUserSelectRect(ByRef X1, ByRef Y1, ByRef X2, ByRef Y2)
{
    static r := 3
    ; Create the "selection rectangle" GUIs (one for each edge).
    Loop 4 {
         Gui, %A_Index%: -Caption +ToolWindow +AlwaysOnTop
        Gui, %A_Index%: Color, Red
     }
    ; Disable LButton.
    Hotkey, *LButton, lusr_return, On
     ; Wait for user to press LButton.
    KeyWait, LButton, D
     ; Get initial coordinates.
    MouseGetPos, xorigin, yorigin
     ; Set timer for updating the selection rectangle.
    SetTimer, lusr_update, 10
     ; Wait for user to release LButton.
    KeyWait, LButton
     ; Re-enable LButton.
    Hotkey, *LButton, Off
     ; Disable timer.
    SetTimer, lusr_update, Off
     ; Destroy "selection rectangle" GUIs.
    Loop 4
         Gui, %A_Index%: Destroy
    return
 
    lusr_update:
        MouseGetPos, x, y
         if (x = xlast && y = ylast)
            ; Mouse hasn't moved so there's nothing to do.
            return
        if (x < xorigin)
             x1 := x, x2 := xorigin
        else x2 := x, x1 := xorigin
         if (y < yorigin)
             y1 := y, y2 := yorigin
        else y2 := y, y1 := yorigin
         ; Update the "selection rectangle".
        Gui, 1:Show, % "NA X" x1 " Y" y1 " W" x2-x1 " H" r
         Gui, 2:Show, % "NA X" x1 " Y" y2-r " W" x2-x1 " H" r
        Gui, 3:Show, % "NA X" x1 " Y" y1 " W" r " H" y2-y1
         Gui, 4:Show, % "NA X" x2-r " Y" y1 " W" r " H" y2-y1
    lusr_return:
    return
}