Gruescript Hidden Code

In the CSS code for a Gruescript game there are style settings for landscape mode, but this code is turned off (placed between comment markers). There is other code like this in the exported games too. Is there a way to turn landscape mode on from within the engine itself? Perhaps with an instruction in the Game Block? I can’t find anything about it in the manual. And is there a way to turn on the other hidden code too, from within the engine?