FileAppend, % "cbSize: " (lastInputInfo ? cbSize : 0) . "`ndwTime: " (lastInputInfo ? dwTime : 0), 1.txt

#include ahkstructlib2.ahk ; http://www.autohotkey.com/board/topic/4613-ahkstructlib-functions-for-use-with-structures-version-2/

cStruct_Create("lastInputInfo"
    , "UInt" , "cbSize"
    , "dword" , "dwTime")
loop
{
    sleep,1000
    DllCall("user32/GetLastInputInfo", "Str", lastInputInfo)
    cStruct_Get("lastInputInfo")
    fileappend, cbSize: %lastInputInfo?cbSize% `n dwTime: %lastInputInfo?dwTime% , 1.txt
}