yes

src/com/mojang/minecraft/level/tile/Glass.java

@@ -15,13 +15,13 @@ public class Glass extends Tile
         //this.setTicking(true);
     }
     
-    @Override
-    public void tick(final Level level, final int x, final int y, final int z, final Random random) {
-        final int below = level.getTile(x, y - 1, z);
+    //@Override
+    //public void tick(final Level level, final int x, final int y, final int z, final Random random) {
+        //final int below = level.getTile(x, y - 1, z);
         //if (!level.isLit(x, y, z) || (below != Tile.dirt.id && below != Tile.grass.id)) {
         //    level.setTile(x, y, z, 0);
         //}
-    }
+    //}
     
     @Override
     public boolean blocksLight() {

src/com/mojang/minecraft/level/tile/GlassDark.java

@@ -0,0 +1,35 @@
+// 
+// Decompiled by Procyon v0.5.36
+// 
+
+package com.mojang.minecraft.level.tile;
+
+import java.util.Random;
+import com.mojang.minecraft.level.Level;
+
+public class GlassDark extends Tile
+{
+    protected GlassDark(final int id) {
+        super(id);
+        this.tex = 50;
+        //this.setTicking(true);
+    }
+    
+    //@Override
+    //public void tick(final Level level, final int x, final int y, final int z, final Random random) {
+        //final int below = level.getTile(x, y - 1, z);
+        //if (!level.isLit(x, y, z) || (below != Tile.dirt.id && below != Tile.grass.id)) {
+        //    level.setTile(x, y, z, 0);
+        //}
+    //}
+    
+    @Override
+    public boolean blocksLight() {
+        return true;
+    }
+    
+    @Override
+    public boolean isSolid() {
+        return true;
+    }
+}

src/com/mojang/minecraft/level/tile/Tile.java

@@ -50,6 +50,7 @@ public class Tile
     public static final Tile BlueGuy;
     public static final Tile BlackMud;
     public static final Tile Glass;
+    public static final Tile DarkGlass;
     public int tex;
     public final int id;
     protected float xx0;
@@ -93,6 +94,7 @@ public class Tile
         BlueGuy = new BlueGuy(28);
         BlackMud = new DarkMud(29);
         Glass = new Glass(30);
+        DarkGlass = new GlassDark(31);
     }
     
     protected Tile(final int id) {