When you fianchetto your bishop, the king will often use the g2/g7 square later on. But what if your opponent does the same, nullifying that advantage? The solution is to go one step further:
1.g4 g6 2.d3 d6 3.Bf4 Bg7 4.Bg3 Nf6 5.Nh3 O-O 6.Nf4 Re8 7.h3 Nbd7 8.e3 c6 9.Be2 Qc7 10.f3 a6 11.O-O b5 12.Rf2 Bb7 13.Kg2!
With this variation you are closer to the center, and with your superior king position you will win in the endgame, unless your opponent tricks you with a cheapo before that.