>>Oh, nothing dangerous, just show printer properties. Another combination is:
>>=Getprinter()
>>press TAB
>>press ENTER
>
>So where do you guys learn about these things? Do you just try lots of things to see what happens?

It's difficult to say. In regard to this specific situation: you may open SYS(1037) compare it with Getprinter() dialog, and you will figure out what's happened during actual development in MS :-).