user2480: 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

user3270: In addition to what Wes said, playing Bh6 isn't even White's main attacking idea in the Dragon and by itself is harmless. I would be happy if my opponent went for Bh6 first. The more dangerous threat is h4-h5, which sometimes is accompanied by Bh6. You should be attacking as quickly as possible on the queenside with b5 and a5, touching the kingside only to stop h4-h5 by playing h7-h5 yourself.

user2130: I've been caught out facing the Dragon by Black players who bring the rook to e8, where attempts to exchange the bishops then fails to 10. ... Nxe4:
[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 Nc6 9. O-O-O Re8 10. Bh6 Nxe4! 11. fxe4 Bxd4

And Black is up a pawn with the option of retreating the bishop.

user2429: 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


2480: <p>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.</p>

<pre><code>[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
</code></pre>

<p>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?</p>

<p>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.</p>

<p>Thanks</p>
 3270: <p>In addition to what Wes said, playing Bh6 isn't even White's main attacking idea in the Dragon and by itself is harmless. I would be happy if my opponent went for Bh6 first. The more dangerous threat is h4-h5, which <strong>sometimes</strong> is accompanied by Bh6. You should be attacking as quickly as possible on the queenside with b5 and a5, touching the kingside only to stop h4-h5 by playing h7-h5 yourself.</p>
 2130: <p>I've been caught out facing the Dragon by Black players who bring the rook to e8, where attempts to exchange the bishops then fails to 10. ... Nxe4:</p>

<pre><code>[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 Nc6 9. O-O-O Re8 10. Bh6 Nxe4! 11. fxe4 Bxd4
</code></pre>

<p>And Black is up a pawn with the option of retreating the bishop.</p>
 2429: <p>Generally, in such type of structures, Black can avoid an exchange by moving away the rook from <strong>f8</strong>, so that when White's bishop comes to <strong>h6</strong>, the Black bishop on <strong>g7</strong> is not pinned to the rook and can move to <strong>h8</strong>. </p>

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

 1...Re8 (1...e6?! 2. Bh6 Bh8? 3. Bxf8)2.Bh6 Bh8
</code></pre>

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

<p>I would suggest that you study the theoretical lines of the dragon variation after <strong>8...Nc6</strong></p>

<pre><code>  [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
</code></pre>
