First attempt at fixing quoted string oddities.

worldedit-core/src/main/java/com/sk89q/worldedit/extension/factory/MaskFactory.java

@@ -42,6 +42,7 @@ import com.sk89q.worldedit.internal.registry.InputParser;
 
 import java.util.ArrayList;
 import java.util.List;
+import java.util.stream.Collectors;
 
 /**
  * A registry of known {@link Mask}s. Provides methods to instantiate
@@ -74,6 +75,16 @@ public final class MaskFactory extends AbstractFactory<Mask> {
         register(new BiomeMaskParser(worldEdit));
     }
 
+    @Override
+    public List<String> getSuggestions(String input) {
+        final String[] split = input.split(" ");
+        if (split.length > 1) {
+            String prev = input.substring(0, input.lastIndexOf(" ")) + " ";
+            return super.getSuggestions(split[split.length -1]).stream().map(s -> prev + s).collect(Collectors.toList());
+        }
+        return super.getSuggestions(input);
+    }
+
     @Override
     public Mask parseFromInput(String input, ParserContext context) throws InputParseException {
         List<Mask> masks = new ArrayList<>();

worldedit-core/src/main/java/com/sk89q/worldedit/internal/command/CommandArgParser.java

@@ -67,16 +67,28 @@ public class CommandArgParser {
                     handleQuote(nextPart);
             }
         }
+        if (currentArg.size() > 0) {
+            finishArg(); // force finish "hanging" args
+        }
         return args.build();
     }
 
     private void handleNormal(Substring part) {
-        if (part.getSubstring().startsWith("\"")) {
-            state = State.QUOTE;
-            currentArg.add(Substring.wrap(
-                part.getSubstring().substring(1),
-                part.getStart(), part.getEnd()
-            ));
+        final String strPart = part.getSubstring();
+        if (strPart.startsWith("\"")) {
+            if (strPart.endsWith("\"") && strPart.length() > 1) {
+                currentArg.add(Substring.wrap(
+                        strPart.substring(1, strPart.length() - 1),
+                        part.getStart(), part.getEnd()
+                ));
+                finishArg();
+            } else {
+                state = State.QUOTE;
+                currentArg.add(Substring.wrap(
+                        strPart.substring(1),
+                        part.getStart(), part.getEnd()
+                ));
+            }
         } else {
             currentArg.add(part);
             finishArg();