Help with using DL and user32.dll to get the active window

ruby-talk
1

I'm still new to ruby and am having trouble working out how to access windows API with DL

So far my code looks like this:

require "dl"
user32 = DL.dlopen('user32')
actwindow = DL::CFunc.new(user32['GetActiveWindow'],type=DL::TYPE_VOID, 'GetActiveWindow')
actwindow.call([])

I realise .call my argument is an empty array, I'm not sure what arguments I should be sending when
the 'GetActiveWindow' method is TYPE_VOID
Any hits in the right direction would be highly appreciated!

GetActiveWindow -> http://msdn.microsoft.com/en-us/library/windows/desktop/ms646292(v=vs.85).aspx