(How) should I avoid bishop exchange in Sicilian (Dragon) style setups? I often play the Sicilian, and out of that, sometimes I end up in situations like the one below, when my dark square bishop is fianchettoed and my opponent is getting ready to get rid of my bishop (after Bh6 the bishop exchange is forced), leaving me with dark square weaknesses.

[FEN ""]

1. e4 c5 2. Nf3 d6 3. d4 cxd4 4. Nxd4 Nf6 5. Nc3 g6 6. Be3 Bg7 7. f3 O-O 8. Qd2


How do you defend in such situations? Is there a general idea or solution to this problem? Or should I just ignore my weakened dark squares and try for a good bishop vs. bad bishop game?

I'm more interested in general tactics than specific lines, in other words, ideas that can be applied to other games, not only this one. This situation can occur for both sides in lots of openings.

Thanks
Generally, in such type of structures, Black can avoid an exchange by moving away the rook from f8, so that when White's bishop comes to h6, the Black bishop on g7 is not pinned to the rook and can move to h8. 

 [FEN "5rk1/4ppbp/6p1/8/8/4B3/3Q4/4K3 b - - 0 1"]

 1...Re8 (1...e6?! 2. Bh6 Bh8? 3. Bxf8)2.Bh6 Bh8


However, in this specific position, White doesn't have time to play Bh6, because Black's counterplay is too strong after 8...Nc6! The only way White can manage the exchange if by playing 9. Nxc6 and then 10. Bh6, but then White doesn't gain much in that line. Black has strong central control and a semi-open b-file for the counter attack. 

I would suggest that you study the theoretical lines of the dragon variation after 8...Nc6

  [FEN "rnbq1rk1/pp2ppbp/3p1np1/8/3NP3/2N1BP2/PPPQ2PP/R3KB1R b KQ - 0 1"]

  1...Nc6 2.Bh6 
  ( 2.Nxc6 bxc6 3.Bh6 Rb8 )
  ( 2.O-O-O d5! )
  2...Bxh6 3.Qxh6 
  ( 3.Nxc6 Bxd2+ )
  3...Nxd4