Added config option to set the default for the /up and /ceil commands.

The config option defaults to glass as that is consistent across gamemodes.
Use -f to force flight (if available).
Use -g to force glass.

src/main/java/com/sk89q/worldedit/LocalConfiguration.java

@@ -101,6 +101,7 @@ public abstract class LocalConfiguration {
     public boolean useInventory = false;
     public boolean useInventoryOverride = false;
     public boolean useInventoryCreativeOverride = false;
+    public boolean navigationUseGlass = true;
     public int navigationWand = ItemID.COMPASS;
     public int navigationWandMaxDistance = 50;
     public int scriptTimeout = 3000;

src/main/java/com/sk89q/worldedit/commands/NavigationCommands.java

@@ -26,6 +26,7 @@ import com.sk89q.minecraft.util.commands.CommandContext;
 import com.sk89q.minecraft.util.commands.CommandPermissions;
 import com.sk89q.minecraft.util.commands.Logging;
 import com.sk89q.worldedit.EditSession;
+import com.sk89q.worldedit.LocalConfiguration;
 import com.sk89q.worldedit.LocalPlayer;
 import com.sk89q.worldedit.LocalSession;
 import com.sk89q.worldedit.WorldEdit;
@@ -118,7 +119,7 @@ public class NavigationCommands {
         aliases = { "ceil" },
         usage = "[clearance]",
         desc = "Go to the celing",
-        flags = "f",
+        flags = "fg",
         min = 0,
         max = 1
     )
@@ -127,11 +128,11 @@ public class NavigationCommands {
     public void ceiling(CommandContext args, LocalSession session, LocalPlayer player,
             EditSession editSession) throws WorldEditException {
 
-        int clearence = args.argsLength() > 0 ?
+        final int clearance = args.argsLength() > 0 ?
             Math.max(0, args.getInteger(0)) : 0;
 
-        final boolean useFlight = args.hasFlag('f');
-        if (player.ascendToCeiling(clearence, !useFlight)) {
+        final boolean alwaysGlass = getAlwaysGlass(args);
+        if (player.ascendToCeiling(clearance, alwaysGlass)) {
             player.print("Whoosh!");
         } else {
             player.printError("No free spot above you found.");
@@ -179,7 +180,7 @@ public class NavigationCommands {
         aliases = { "up" },
         usage = "<block>",
         desc = "Go upwards some distance",
-        flags = "f",
+        flags = "fg",
         min = 1,
         max = 1
     )
@@ -188,13 +189,28 @@ public class NavigationCommands {
     public void up(CommandContext args, LocalSession session, LocalPlayer player,
             EditSession editSession) throws WorldEditException {
 
-        int distance = args.getInteger(0);
+        final int distance = args.getInteger(0);
 
-        final boolean useFlight = args.hasFlag('f');
-        if (player.ascendUpwards(distance, !useFlight)) {
+        final boolean alwaysGlass = getAlwaysGlass(args);
+        if (player.ascendUpwards(distance, alwaysGlass)) {
             player.print("Whoosh!");
         } else {
             player.printError("You would hit something above you.");
         }
     }
+
+    /**
+     * Helper function for /up and /ceil.
+     * 
+     * @param args The {@link CommandContext} to extract the flags from.
+     * @return true, if glass should always be put under the player
+     */
+    private boolean getAlwaysGlass(CommandContext args) {
+        final LocalConfiguration config = we.getConfiguration();
+
+        final boolean forceFlight = args.hasFlag('f');
+        final boolean forceGlass = args.hasFlag('g');
+
+        return forceGlass || (config.navigationUseGlass && !forceFlight);
+    }
 }

src/main/java/com/sk89q/worldedit/util/PropertiesConfiguration.java

@@ -101,6 +101,7 @@ public class PropertiesConfiguration extends LocalConfiguration {
         useInventoryCreativeOverride = getBool("use-inventory-creative-override", useInventoryCreativeOverride);
         navigationWand = getInt("nav-wand-item", navigationWand);
         navigationWandMaxDistance = getInt("nav-wand-distance", navigationWandMaxDistance);
+        navigationUseGlass = getBool("nav-use-glass", navigationUseGlass);
         scriptTimeout = getInt("scripting-timeout", scriptTimeout);
         saveDir = getString("schematic-save-dir", saveDir);
         scriptsDir = getString("craftscript-dir", scriptsDir);

src/main/java/com/sk89q/worldedit/util/YAMLConfiguration.java

@@ -98,6 +98,7 @@ public class YAMLConfiguration extends LocalConfiguration {
 
         navigationWand = config.getInt("navigation-wand.item", navigationWand);
         navigationWandMaxDistance = config.getInt("navigation-wand.max-distance", navigationWandMaxDistance);
+        navigationUseGlass = config.getBoolean("navigation.use-glass", navigationUseGlass);
 
         scriptTimeout = config.getInt("scripting.timeout", scriptTimeout);
         scriptsDir = config.getString("scripting.dir", scriptsDir);