An obvious solution would be to use the "SendKeys" method, which can be used to "type" ALT+W and N, but I haven't been able to make it work. I'm not sure whether I'm making some mistake or that Cardbox simply doesn't respond to SendKeys.
There is however a script language, similar to VBscript, that is called Autoit3 (www.autoitscript.com). You can use it to script any application and even Windows itself. It is very easy to use, you can merge the commands with the Cardbox macro language, it's very small (± 123 kb), well-documented, and it's free. I managed to make a new window in Cardbox using a one-line Autoit3 script: Send("%wn").
Autoit3 scripts can be compiled to .exe which I did with the above mentioned oneliner. You can either download Autoit3 yourself and have a good time doing all the things Vbscript can't do (recommended), or you can download my "newwindow.exe" using the following link:
Make a Cardbox macro launch the newwindow.exe and your done.
first: the above mentioned line Send("%wn") should be Send(!wn"). My mistake.
Second: in one of your earlier messages (Complex Database) you asked about changing drop-down lists in the format file. I tried to use Autoit3 to do this and it works perfectly. It takes just one line of code to open the format, i.e. Send("!efe"), another to move the mouse to the right field and click it (mousemove("left",X,Y) and a third to send ALT+ENTER. You are then in the Field Properties box.
Autoit3 has a small utility that you can use to retrieve window information and it shows the coordinates of the mouse pointer, so you can easily determine where the mouse should move to. You can even allow for different screen resolutions.