diff --git a/pdex/src/processing/mode/experimental/ASTGenerator.java b/pdex/src/processing/mode/experimental/ASTGenerator.java
index ebda1f9ea..141c3888c 100644
--- a/pdex/src/processing/mode/experimental/ASTGenerator.java
+++ b/pdex/src/processing/mode/experimental/ASTGenerator.java
@@ -240,7 +240,7 @@ public class ASTGenerator {
   /**
    * Toggle AST View window
    */
-  public static final boolean SHOWAST = !true;
+  public static final boolean SHOWAST = true;
 
   protected DefaultMutableTreeNode buildAST(String source, CompilationUnit cu) {
     if (cu == null) {
@@ -794,6 +794,13 @@ public class ASTGenerator {
   
   private AtomicBoolean predictionOngoing;
   
+  /**
+   * The main function that calculates possible code completion candidates
+   *  
+   * @param word
+   * @param line
+   * @param lineStartNonWSOffset
+   */
   public void preparePredictions(final String word, final int line, final int lineStartNonWSOffset) {
     if(predictionOngoing.get()) return;
         
@@ -890,11 +897,14 @@ public class ASTGenerator {
           MethodInvocation mi = (MethodInvocation)testnode;
           System.out.println(mi.getName() + "," + mi.getExpression() + "," + mi.typeArguments().size());
         }
+        
+        // find nearest ASTNode
         nearestNode = findClosestNode(lineNumber, (ASTNode) compilationUnit.types()
             .get(0));
-        if (nearestNode == null)
-          //Make sure nearestNode is not NULL if couldn't find a closeset node
+        if (nearestNode == null) {
+          // Make sure nearestNode is not NULL if couldn't find a closeset node
           nearestNode = (ASTNode) compilationUnit.types().get(0);
+        }
         logE(lineNumber + " Nearest ASTNode to PRED "
             + getNodeAsString(nearestNode));
 
diff --git a/pdex/src/processing/mode/experimental/ErrorCheckerService.java b/pdex/src/processing/mode/experimental/ErrorCheckerService.java
index 92948c09a..e4885a37f 100644
--- a/pdex/src/processing/mode/experimental/ErrorCheckerService.java
+++ b/pdex/src/processing/mode/experimental/ErrorCheckerService.java
@@ -36,11 +36,9 @@ import java.util.concurrent.atomic.AtomicInteger;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
-import javax.swing.JCheckBoxMenuItem;
 import javax.swing.event.DocumentEvent;
 import javax.swing.event.DocumentListener;
 import javax.swing.table.DefaultTableModel;
-import javax.swing.text.AbstractDocument;
 
 import org.eclipse.jdt.core.JavaCore;
 import org.eclipse.jdt.core.compiler.IProblem;
@@ -137,7 +135,7 @@ public class ErrorCheckerService implements Runnable{
   /**
    * Compilation Unit for current sketch
    */
-  protected CompilationUnit cu;
+  protected CompilationUnit cu, lastCorrectCu;
 
   /**
    * If true, compilation checker will be reloaded with updated classpath
@@ -537,7 +535,10 @@ public class ErrorCheckerService implements Runnable{
       if (problems.length == 0) {
         syntaxErrors.set(false);
         containsErrors.set(false);
+        lastCorrectCu = cu;
       } else {
+        CompilationUnit cuTemp = null;
+        lastCorrectCu = cuTemp;
         syntaxErrors.set(true);
         containsErrors.set(true);
       }
@@ -548,7 +549,8 @@ public class ErrorCheckerService implements Runnable{
   
   protected void compileCheck() {
     
-    // CU needs to be updated coz before compileCheck xqpreprocessor is run on the source code which makes some further changes
+    // CU needs to be updated coz before compileCheck xqpreprocessor is run on 
+    // the source code which makes some further changes
     //TODO Check if this breaks things 
     
     parser.setSource(sourceCode.toCharArray());
@@ -565,6 +567,7 @@ public class ErrorCheckerService implements Runnable{
       cu = (CompilationUnit) parser.createAST(null);
     else {
       synchronized (cu) {
+        if (!hasSyntaxErrors())
         cu = (CompilationUnit) parser.createAST(null);
       }
     }