Script to navigate to next or previous document

Hi,

since CC it's impossible to assign the shortcut CTRL-TAB to "next document" and CTRL-SHIFT-TAB to "previous document"

what I found out is, that it is possible to assign these shortcuts to a script, so, if I had a script that go's to next document and one to go to previous document, I can assign those shortcuts to these scripts and my problem is solved (in a way)

So now I have two little questions,

1. how to make a script that takes me to the next  document

2. how to make a script that takes me to the previous  document

I know how to edit scripts, but scripting itself is like Chinese for me :-)

Thanks in advance for helping me out!