diff --git a/java/src/processing/mode/java/JavaEditor.java b/java/src/processing/mode/java/JavaEditor.java
index d9d5508be..7ec79c433 100644
--- a/java/src/processing/mode/java/JavaEditor.java
+++ b/java/src/processing/mode/java/JavaEditor.java
@@ -29,7 +29,7 @@ import processing.app.ui.Toolkit;
 import processing.mode.java.debug.LineBreakpoint;
 import processing.mode.java.debug.LineHighlight;
 import processing.mode.java.debug.LineID;
-import processing.mode.java.pdex.ErrorCheckerService;
+import processing.mode.java.pdex.PreprocessingService;
 import processing.mode.java.pdex.ImportStatement;
 import processing.mode.java.pdex.JavaTextArea;
 import processing.mode.java.pdex.PDEX;
@@ -70,7 +70,7 @@ public class JavaEditor extends Editor {
   private boolean hasJavaTabs;
   private boolean javaTabWarned;
 
-  protected ErrorCheckerService errorCheckerService;
+  protected PreprocessingService preprocessingService;
   protected PDEX pdex;
 
   protected List<Problem> problems = Collections.emptyList();
@@ -150,7 +150,7 @@ public class JavaEditor extends Editor {
 
     getJavaTextArea().setMode(jmode);
 
-    initErrorChecker();
+    initPDEX();
 
     // ensure completion is hidden when editor loses focus
     addWindowFocusListener(new WindowFocusListener() {
@@ -174,18 +174,9 @@ public class JavaEditor extends Editor {
   }
   
   
-  protected void initErrorChecker() {
-    errorCheckerService = new ErrorCheckerService(this);
-    for (SketchCode code : getSketch().getCode()) {
-      Document document = code.getDocument();
-      if (document != null) {
-        errorCheckerService.addDocumentListener(document);
-      }
-    }
-    errorCheckerService.start();
-    errorCheckerService.notifySketchChanged();
-
-    pdex = new PDEX(this, errorCheckerService);
+  protected void initPDEX() {
+    preprocessingService = new PreprocessingService(this);
+    pdex = new PDEX(this, preprocessingService);
 
     // Add ctrl+click listener
     getJavaTextArea().getPainter().addMouseListener(new MouseAdapter() {
@@ -199,6 +190,44 @@ public class JavaEditor extends Editor {
         }
       }
     });
+
+    sketchChanged();
+
+    for (SketchCode code : getSketch().getCode()) {
+      Document document = code.getDocument();
+      if (document != null) {
+        addDocumentListener(document);
+      }
+    }
+  }
+
+
+  public void addDocumentListener(Document doc) {
+    if (doc != null) doc.addDocumentListener(sketchChangedListener);
+  }
+
+
+  protected final DocumentListener sketchChangedListener = new DocumentListener() {
+    @Override
+    public void insertUpdate(DocumentEvent e) {
+      sketchChanged();
+    }
+
+    @Override
+    public void removeUpdate(DocumentEvent e) {
+      sketchChanged();
+    }
+
+    @Override
+    public void changedUpdate(DocumentEvent e) {
+      sketchChanged();
+    }
+  };
+
+
+  protected void sketchChanged() {
+    pdex.notifySketchChanged();
+    preprocessingService.notifySketchChanged();
   }
   
   
@@ -214,6 +243,7 @@ public class JavaEditor extends Editor {
 
   private int previousTabCount = 1;
 
+  // TODO: this is a clumsy way to get notified when tabs get added/deleted
   // Override the parent call to add hook to the rebuild() method
   public EditorHeader createHeader() {
     return new EditorHeader(this) {
@@ -225,9 +255,9 @@ public class JavaEditor extends Editor {
         boolean hasJavaTabsChanged = hasJavaTabs != newHasJavaTabs;
         hasJavaTabs = newHasJavaTabs;
 
-        if (errorCheckerService != null) {
+        if (preprocessingService != null) {
           if (hasJavaTabsChanged) {
-            errorCheckerService.handleHasJavaTabsChange(hasJavaTabs);
+            preprocessingService.handleHasJavaTabsChange(hasJavaTabs);
             pdex.handleHasJavaTabsChange(hasJavaTabs);
             if (hasJavaTabs) {
               setProblemList(Collections.emptyList());
@@ -237,7 +267,7 @@ public class JavaEditor extends Editor {
           int currentTabCount = sketch.getCodeCount();
           if (currentTabCount != previousTabCount) {
             previousTabCount = currentTabCount;
-            errorCheckerService.notifySketchChanged();
+            sketchChanged();
           }
         }
       }
@@ -1327,13 +1357,13 @@ public class JavaEditor extends Editor {
 
   @Override
   public void librariesChanged() {
-    errorCheckerService.notifyLibrariesChanged();
+    preprocessingService.notifyLibrariesChanged();
   }
 
 
   @Override
   public void codeFolderChanged() {
-    errorCheckerService.notifyCodeFolderChanged();
+    preprocessingService.notifyCodeFolderChanged();
   }
 
 
@@ -1374,111 +1404,12 @@ public class JavaEditor extends Editor {
     if (inspector != null) {
       inspector.dispose();
     }
-    errorCheckerService.stop();
+    preprocessingService.dispose();
     pdex.dispose();
     super.dispose();
   }
 
 
-  // Not sure how this was supposed to work, tempErrorLog is always empty [jv]
-  /**
-   * Writes all error messages to a csv file.
-   * For analytics purposes only.
-   */
-  /*
-  private void writeErrorsToFile() {
-    if (errorCheckerService.tempErrorLog.size() == 0) return;
-
-    try {
-      System.out.println("Writing errors");
-      StringBuilder sb = new StringBuilder();
-      sb.append("Sketch: " + getSketch().getFolder() + ", "
-                + new java.sql.Timestamp(new java.util.Date().getTime())
-                + "\nComma in error msg is substituted with ^ symbol\nFor separating arguments in error args | symbol is used\n");
-      sb.append("ERROR TYPE, ERROR ARGS, ERROR MSG\n");
-
-      for (String errMsg : errorCheckerService.tempErrorLog.keySet()) {
-        IProblem ip = errorCheckerService.tempErrorLog.get(errMsg);
-        if (ip != null) {
-          sb.append(ErrorMessageSimplifier.getIDName(ip.getID()));
-          sb.append(',');
-          sb.append("{");
-          for (int i = 0; i < ip.getArguments().length; i++) {
-            sb.append(ip.getArguments()[i]);
-            if (i < ip.getArguments().length-1)
-              sb.append("| ");
-          }
-          sb.append("}");
-          sb.append(',');
-          sb.append(ip.getMessage().replace(',', '^'));
-          sb.append("\n");
-        }
-      }
-      System.out.println(sb);
-      File opFile = new File(getSketch().getFolder(), "ErrorLogs"
-                             + File.separator + "ErrorLog_" + System.currentTimeMillis() + ".csv");
-      PApplet.saveStream(opFile, new ByteArrayInputStream(sb.toString()
-                                                          .getBytes(Charset.defaultCharset())));
-    } catch (Exception e) {
-      System.err.println("Failed to save log file for sketch " + getSketch().getName());
-      e.printStackTrace();
-    }
-  }*/
-
-
-  /*
-    private AtomicBoolean debugToolbarEnabled;
-
-    public boolean isDebugToolbarEnabled() {
-      return debugToolbarEnabled != null && debugToolbarEnabled.get();
-    }
-
-
-    /// Toggles between java mode and debug mode toolbar
-    protected void switchToolbars(){
-      final EditorToolbar nextToolbar;
-      if(debugToolbarEnabled.get()){
-        // switch to java
-        if(javaToolbar == null)
-          javaToolbar = createToolbar();
-        nextToolbar = javaToolbar;
-        debugToolbarEnabled.set(false);
-        Base.log("Switching to Java Mode Toolbar");
-      }
-      else{
-        // switch to debug
-        if(debugToolbar == null)
-          debugToolbar = new DebugToolbar(this, getBase());
-        nextToolbar = debugToolbar;
-        debugToolbarEnabled.set(true);
-        Base.log("Switching to Debugger Toolbar");
-      }
-
-      SwingUtilities.invokeLater(new Runnable() {
-        public void run() {
-          Box upper = (Box)splitPane.getComponent(0);
-          upper.remove(0);
-          upper.add(nextToolbar, 0);
-          upper.validate();
-          nextToolbar.repaint();
-          toolbar = nextToolbar;
-          // The toolbar responds to shift down/up events
-          // in order to show the alt version of toolbar buttons.
-          // With toolbar switch, KeyListener has to be changed as well
-          for (KeyListener kl : textarea.getKeyListeners()) {
-            if(kl instanceof EditorToolbar)
-            {
-              textarea.removeKeyListener(kl);
-              textarea.addKeyListener(toolbar);
-              break;
-            }
-          }
-          textarea.repaint();
-        }
-      });
-    }
-  */
-
   /**
    * Creates the debug menu. Includes ActionListeners for the menu items.
    * Intended for adding to the menu bar.
@@ -1660,26 +1591,6 @@ public class JavaEditor extends Editor {
 //      });
 //    debugMenu.add(item);
 
-    /*
-    item = Toolkit.newJMenuItem(Language.text("menu.debug.show_sketch_outline"), KeyEvent.VK_L);
-    item.addActionListener(new ActionListener() {
-        public void actionPerformed(ActionEvent e) {
-          Messages.log("Show Sketch Outline:");
-          errorCheckerService.getASTGenerator().showSketchOutline();
-        }
-      });
-    debugMenu.add(item);
-
-    item = Toolkit.newJMenuItem(Language.text("menu.debug.show_tabs_list"), KeyEvent.VK_Y);
-    item.addActionListener(new ActionListener() {
-        public void actionPerformed(ActionEvent e) {
-          Messages.log("Show Tab Outline:");
-          errorCheckerService.getASTGenerator().showTabOutline();
-        }
-      });
-    debugMenu.add(item);
-    */
-
     return debugMenu;
   }
 
@@ -1928,8 +1839,8 @@ public class JavaEditor extends Editor {
   }
 
 
-  public ErrorCheckerService getErrorChecker() {
-    return errorCheckerService;
+  public PreprocessingService getPreprocessingService() {
+    return preprocessingService;
   }
 
 
@@ -1942,7 +1853,7 @@ public class JavaEditor extends Editor {
     autoSave();
     super.prepareRun();
     downloadImports();
-    errorCheckerService.cancel();
+    preprocessingService.cancel();
   }
 
 
@@ -2388,8 +2299,8 @@ public class JavaEditor extends Editor {
     super.setCode(code);
 
     Document newDoc = code.getDocument();
-    if (oldDoc != newDoc && errorCheckerService != null) {
-      errorCheckerService.addDocumentListener(newDoc);
+    if (oldDoc != newDoc && preprocessingService != null) {
+      addDocumentListener(newDoc);
     }
 
     // set line background colors for tab
@@ -2529,24 +2440,6 @@ public class JavaEditor extends Editor {
   */
 
 
-//  /**
-//   * Initializes and starts Error Checker Service
-//   */
-//  private void initializeErrorChecker() {
-//    Thread errorCheckerThread = null;
-//
-//    if (errorCheckerThread == null) {
-//      errorCheckerService = new ErrorCheckerService(this);
-//      errorCheckerThread = new Thread(errorCheckerService);
-//      try {
-//        errorCheckerThread.start();
-//      } catch (Exception e) {
-//        Base.loge("Error Checker Service not initialized", e);
-//      }
-//    }
-//  }
-
-
   public void setProblemList(List<Problem> problems) {
     this.problems = problems;
     boolean hasErrors = problems.stream().anyMatch(Problem::isError);
@@ -2566,7 +2459,7 @@ public class JavaEditor extends Editor {
 
     for (Problem p : problems) {
       String message = p.getMessage();
-      if (Preferences.getBoolean(JavaMode.SUGGEST_IMPORTS_PREF) &&
+      if (JavaMode.importSuggestEnabled &&
           p.getImportSuggestions() != null &&
           p.getImportSuggestions().length > 0) {
         message += " (double-click for suggestions)";
@@ -2616,19 +2509,17 @@ public class JavaEditor extends Editor {
    * line or not
    */
   public void updateEditorStatus() {
-    if (JavaMode.errorCheckEnabled) {
-      Problem problem = findError(textarea.getCaretLine());
-      if (problem != null) {
-        int type = problem.isError() ?
-            EditorStatus.CURSOR_LINE_ERROR : EditorStatus.CURSOR_LINE_WARNING;
-        statusMessage(problem.getMessage(), type);
-      } else {
-        switch (getStatusMode()) {
-          case EditorStatus.CURSOR_LINE_ERROR:
-          case EditorStatus.CURSOR_LINE_WARNING:
-            statusEmpty();
-            break;
-        }
+    Problem problem = findError(textarea.getCaretLine());
+    if (problem != null) {
+      int type = problem.isError() ?
+          EditorStatus.CURSOR_LINE_ERROR : EditorStatus.CURSOR_LINE_WARNING;
+      statusMessage(problem.getMessage(), type);
+    } else {
+      switch (getStatusMode()) {
+        case EditorStatus.CURSOR_LINE_ERROR:
+        case EditorStatus.CURSOR_LINE_WARNING:
+          statusEmpty();
+          break;
       }
     }
   }
@@ -2797,16 +2688,13 @@ public class JavaEditor extends Editor {
    * the error button at the bottom of the PDE
    */
   public void updateErrorToggle(boolean hasErrors) {
-    footer.setNotification(errorTable.getParent(),  //errorTableScrollPane,
-                           JavaMode.errorCheckEnabled &&
-                           hasErrors);
+    footer.setNotification(errorTable.getParent(), hasErrors);
 //    String title = Language.text("editor.footer.errors");
-//    if (JavaMode.errorCheckEnabled && errorCheckerService.hasErrors()) {
+//    if (hasErrors) {
 //      title += "*";
 //    }
 //    ((JTabbedPane) footer).setTitleAt(ERROR_TAB_INDEX, title);
-////    btnShowErrors.updateMarker(JavaMode.errorCheckEnabled &&
-////                               errorCheckerService.hasErrors(),
+////    btnShowErrors.updateMarker(hasErrors,
 ////                               errorBar.errorColor);
   }
 
@@ -2875,8 +2763,7 @@ public class JavaEditor extends Editor {
       jmode.loadPreferences();
       Messages.log("Applying prefs");
       // trigger it once to refresh UI
-      errorCheckerService.handlePreferencesChange();
-      setProblemList(Collections.emptyList());
+      sketchChanged();
     }
   }
 
diff --git a/java/src/processing/mode/java/JavaMode.java b/java/src/processing/mode/java/JavaMode.java
index ed9d4e3e3..d15348c24 100644
--- a/java/src/processing/mode/java/JavaMode.java
+++ b/java/src/processing/mode/java/JavaMode.java
@@ -117,33 +117,6 @@ public class JavaMode extends Mode {
   // . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
 
 
-  /*
-  public Runner handleRun(Sketch sketch,
-                          RunnerListener listener) throws SketchException {
-    final JavaEditor editor = (JavaEditor) listener;
-    editor.errorCheckerService.quickErrorCheck();
-//    if (enableTweak) {
-//      enableTweak = false;
-//      return handleTweak(sketch, listener, false);
-//    } else {
-    return handleLaunch(sketch, listener, false);
-//    }
-  }
-
-
-  public Runner handlePresent(Sketch sketch,
-                              RunnerListener listener) throws SketchException {
-    final JavaEditor editor = (JavaEditor) listener;
-    editor.errorCheckerService.quickErrorCheck();
-//    if (enableTweak) {
-//      enableTweak = false;
-//      return handleTweak(sketch, listener, true);
-//    } else {
-    return handleLaunch(sketch, listener, true);
-//    }
-  }
-  */
-
 
   /** Handles the standard Java "Run" or "Present" */
   public Runner handleLaunch(Sketch sketch, RunnerListener listener,
@@ -174,7 +147,6 @@ public class JavaMode extends Mode {
                             RunnerListener listener) throws SketchException {
 //                            final boolean present) throws SketchException {
     final JavaEditor editor = (JavaEditor) listener;
-//    editor.errorCheckerService.quickErrorCheck();  // done in prepareRun()
 
     if (isSketchModified(sketch)) {
       editor.deactivateRun();
@@ -334,7 +306,7 @@ public class JavaMode extends Mode {
 //  }
 
 
-  static public volatile boolean errorCheckEnabled = true;
+//  static public volatile boolean errorCheckEnabled = true;
   static public volatile boolean warningsEnabled = true;
   static public volatile boolean codeCompletionsEnabled = true;
   static public volatile boolean debugOutputEnabled = false;
@@ -343,7 +315,7 @@ public class JavaMode extends Mode {
   static public volatile boolean autoSavePromptEnabled = true;
   static public volatile boolean defaultAutoSaveEnabled = true;
   static public volatile boolean ccTriggerEnabled = false;
-//  static public volatile boolean importSuggestEnabled = true;
+  static public volatile boolean importSuggestEnabled = true;
   static public int autoSaveInterval = 3; //in minutes
 
 
@@ -352,7 +324,7 @@ public class JavaMode extends Mode {
    */
   volatile public static int codeCompletionTriggerLength = 1;
 
-  static public final String prefErrorCheck = "pdex.errorCheckEnabled";
+//  static public final String prefErrorCheck = "pdex.errorCheckEnabled";
   static public final String prefWarnings = "pdex.warningsEnabled";
   static public final String prefDebugOP = "pdex.dbgOutput";
   static public final String prefErrorLogs = "pdex.writeErrorLogs";
@@ -377,7 +349,7 @@ public class JavaMode extends Mode {
   public void loadPreferences() {
     Messages.log("Load PDEX prefs");
     ensurePrefsExist();
-    errorCheckEnabled = Preferences.getBoolean(prefErrorCheck);
+//    errorCheckEnabled = Preferences.getBoolean(prefErrorCheck);
     warningsEnabled = Preferences.getBoolean(prefWarnings);
     codeCompletionsEnabled = Preferences.getBoolean(COMPLETION_PREF);
 //    DEBUG = Preferences.getBoolean(prefDebugOP);
@@ -388,14 +360,14 @@ public class JavaMode extends Mode {
     autoSavePromptEnabled = Preferences.getBoolean(prefAutoSavePrompt);
     defaultAutoSaveEnabled = Preferences.getBoolean(prefDefaultAutoSave);
     ccTriggerEnabled = Preferences.getBoolean(COMPLETION_TRIGGER_PREF);
-//    importSuggestEnabled = Preferences.getBoolean(prefImportSuggestEnabled);
+    importSuggestEnabled = Preferences.getBoolean(SUGGEST_IMPORTS_PREF);
     loadSuggestionsMap();
   }
 
 
   public void savePreferences() {
     Messages.log("Saving PDEX prefs");
-    Preferences.setBoolean(prefErrorCheck, errorCheckEnabled);
+//    Preferences.setBoolean(prefErrorCheck, errorCheckEnabled);
     Preferences.setBoolean(prefWarnings, warningsEnabled);
     Preferences.setBoolean(COMPLETION_PREF, codeCompletionsEnabled);
 //    Preferences.setBoolean(prefDebugOP, DEBUG);
@@ -406,7 +378,7 @@ public class JavaMode extends Mode {
     Preferences.setBoolean(prefAutoSavePrompt, autoSavePromptEnabled);
     Preferences.setBoolean(prefDefaultAutoSave, defaultAutoSaveEnabled);
     Preferences.setBoolean(COMPLETION_TRIGGER_PREF, ccTriggerEnabled);
-//    Preferences.setBoolean(prefImportSuggestEnabled, importSuggestEnabled);
+    Preferences.setBoolean(SUGGEST_IMPORTS_PREF, importSuggestEnabled);
   }
 
   public void loadSuggestionsMap() {
@@ -453,8 +425,8 @@ public class JavaMode extends Mode {
 
   public void ensurePrefsExist() {
     //TODO: Need to do a better job of managing prefs. Think lists.
-    if (Preferences.get(prefErrorCheck) == null)
-      Preferences.setBoolean(prefErrorCheck, errorCheckEnabled);
+//    if (Preferences.get(prefErrorCheck) == null)
+//      Preferences.setBoolean(prefErrorCheck, errorCheckEnabled);
     if (Preferences.get(prefWarnings) == null)
       Preferences.setBoolean(prefWarnings, warningsEnabled);
     if (Preferences.get(COMPLETION_PREF) == null)
@@ -475,8 +447,8 @@ public class JavaMode extends Mode {
       Preferences.setBoolean(prefDefaultAutoSave, defaultAutoSaveEnabled);
     if (Preferences.get(COMPLETION_TRIGGER_PREF) == null)
       Preferences.setBoolean(COMPLETION_TRIGGER_PREF, ccTriggerEnabled);
-//    if (Preferences.get(prefImportSuggestEnabled) == null)
-//      Preferences.setBoolean(prefImportSuggestEnabled, importSuggestEnabled);
+    if (Preferences.get(SUGGEST_IMPORTS_PREF) == null)
+      Preferences.setBoolean(SUGGEST_IMPORTS_PREF, importSuggestEnabled);
   }
 
 
diff --git a/java/src/processing/mode/java/pdex/CompletionGenerator.java b/java/src/processing/mode/java/pdex/CompletionGenerator.java
index 364e786fe..6ccc639d5 100644
--- a/java/src/processing/mode/java/pdex/CompletionGenerator.java
+++ b/java/src/processing/mode/java/pdex/CompletionGenerator.java
@@ -61,6 +61,7 @@ import org.eclipse.jdt.core.dom.VariableDeclarationFragment;
 import org.eclipse.jdt.core.dom.VariableDeclarationStatement;
 
 import processing.app.Messages;
+import processing.mode.java.JavaMode;
 
 import com.google.classpath.ClassPath;
 import com.google.classpath.RegExpResourceFilter;
@@ -687,8 +688,6 @@ public class CompletionGenerator {
       return null;
     }
 
-    //PreprocessedSketch ps = ecs.requestResult();
-
     if (className.indexOf('.') >= 0) {
       // Figure out what is package and what is class
       String[] parts = className.split("\\.");
@@ -1319,6 +1318,41 @@ public class CompletionGenerator {
   }
 
 
+  protected static boolean ignorableSuggestionImport(PreprocessedSketch ps, String impName) {
+
+    String impNameLc = impName.toLowerCase();
+
+    List<ImportStatement> programImports = ps.programImports;
+    List<ImportStatement> codeFolderImports = ps.codeFolderImports;
+
+    boolean isImported = Stream
+        .concat(programImports.stream(), codeFolderImports.stream())
+        .anyMatch(impS -> {
+          String packageNameLc = impS.getPackageName().toLowerCase();
+          return impNameLc.startsWith(packageNameLc);
+        });
+
+    if (isImported) return false;
+
+    final String include = "include";
+    final String exclude = "exclude";
+
+    if (impName.startsWith("processing")) {
+      if (JavaMode.suggestionsMap.containsKey(include) && JavaMode.suggestionsMap.get(include).contains(impName)) {
+        return false;
+      } else if (JavaMode.suggestionsMap.containsKey(exclude) && JavaMode.suggestionsMap.get(exclude).contains(impName)) {
+        return true;
+      }
+    } else if (impName.startsWith("java")) {
+      if (JavaMode.suggestionsMap.containsKey(include) && JavaMode.suggestionsMap.get(include).contains(impName)) {
+        return false;
+      }
+    }
+
+    return true;
+  }
+
+
   /**
    * A wrapper for java.lang.reflect types.
    * Will have to see if the usage turns out to be internal only here or not
@@ -1850,7 +1884,7 @@ public class CompletionGenerator {
           matchedClass2 = matchedClass2.replace('/', '.'); //package name
           String matchedClass = matchedClass2.substring(0, matchedClass2.length() - 6);
           int d = matchedClass.lastIndexOf('.');
-          if (!ErrorCheckerService.ignorableSuggestionImport(ps, matchedClass)) {
+          if (!ignorableSuggestionImport(ps, matchedClass)) {
             matchedClass = matchedClass.substring(d + 1); //class name
             // display package name in grey
             String html = "<html>" + matchedClass + " : <font color=#777777>" +
diff --git a/java/src/processing/mode/java/pdex/JavaTextArea.java b/java/src/processing/mode/java/pdex/JavaTextArea.java
index 9ef3f6d2e..09ba709f3 100644
--- a/java/src/processing/mode/java/pdex/JavaTextArea.java
+++ b/java/src/processing/mode/java/pdex/JavaTextArea.java
@@ -322,7 +322,7 @@ public class JavaTextArea extends JEditTextArea {
     int codeIndex = editor.getSketch().getCodeIndex(editor.getCurrentTab());
     int lineStartOffset = editor.getTextArea().getLineStartOffset(caretLineIndex);
 
-    editor.getErrorChecker().acceptWhenDone(ps -> {
+    editor.getPreprocessingService().whenDone(ps -> {
       int lineNumber = ps.tabOffsetToJavaLine(codeIndex, lineStartOffset);
 
       String phrase = null;
diff --git a/java/src/processing/mode/java/pdex/JavaTextAreaPainter.java b/java/src/processing/mode/java/pdex/JavaTextAreaPainter.java
index 286b9a79a..4d891893b 100644
--- a/java/src/processing/mode/java/pdex/JavaTextAreaPainter.java
+++ b/java/src/processing/mode/java/pdex/JavaTextAreaPainter.java
@@ -342,7 +342,7 @@ public class JavaTextAreaPainter extends TextAreaPainter
 
 
   /**
-   * Sets ErrorCheckerService and loads theme for TextAreaPainter(XQMode)
+   * Loads theme for TextAreaPainter(XQMode)
    */
   public void setMode(Mode mode) {
     errorUnderlineColor = mode.getColor("editor.error.underline.color");
@@ -385,96 +385,6 @@ public class JavaTextAreaPainter extends TextAreaPainter
   }
 
 
-  /*
-  @Override
-  public String getToolTipText(MouseEvent event) {
-    if (!getJavaEditor().hasJavaTabs()) {
-      int off = textArea.xyToOffset(event.getX(), event.getY());
-      if (off < 0) {
-        setToolTipText(null);
-        return super.getToolTipText(event);
-      }
-      int line = textArea.getLineOfOffset(off);
-      if (line < 0) {
-        setToolTipText(null);
-        return super.getToolTipText(event);
-      }
-
-      String s = textArea.getLineText(line);
-      if (s == null || s.isEmpty()) {
-        setToolTipText(null);
-        return super.getToolTipText(event);
-
-      } else {
-        int x = textArea.xToOffset(line, event.getX()), x2 = x + 1, x1 = x - 1;
-        int xLS = off - textArea.getLineStartNonWhiteSpaceOffset(line);
-        if (x < 0 || x >= s.length()) {
-          setToolTipText(null);
-          return super.getToolTipText(event);
-        }
-        String word = s.charAt(x) + "";
-        if (s.charAt(x) == ' ') {
-          setToolTipText(null);
-          return super.getToolTipText(event);
-        }
-        if (!(Character.isLetterOrDigit(s.charAt(x)) ||
-            s.charAt(x) == '_' || s.charAt(x) == '$' || s.charAt(x) == '{' ||
-            s.charAt(x) == '}')) {
-          setToolTipText(null);
-          return super.getToolTipText(event);
-        }
-        int i = 0;
-        while (true) {
-          i++;
-          if (x1 >= 0 && x1 < s.length()) {
-            if (Character.isLetter(s.charAt(x1)) || s.charAt(x1) == '_') {
-              word = s.charAt(x1--) + word;
-              xLS--;
-            } else
-              x1 = -1;
-          } else
-            x1 = -1;
-
-          if (x2 >= 0 && x2 < s.length()) {
-            if (Character.isLetterOrDigit(s.charAt(x2)) || s.charAt(x2) == '_'
-                || s.charAt(x2) == '$')
-              word = word + s.charAt(x2++);
-            else
-              x2 = -1;
-          } else
-            x2 = -1;
-
-          if (x1 < 0 && x2 < 0)
-            break;
-          if (i > 200) {
-            // time out!
-            // System.err.println("Whoopsy! :P");
-            break;
-          }
-        }
-        if (Character.isDigit(word.charAt(0))) {
-          setToolTipText(null);
-          return super.getToolTipText(event);
-        }
-        ASTGenerator ast = getJavaEditor().getErrorChecker().getASTGenerator();
-        synchronized (ast) {
-          String tooltipText = ast.getLabelForASTNode(line, word, xLS);
-
-          //      log(errorCheckerService.mainClassOffset + " MCO "
-          //      + "|" + line + "| offset " + xLS + word + " <= offf: "+off+ "\n");
-          if (tooltipText != null) {
-            return tooltipText;
-          }
-        }
-      }
-    }
-    // Used when there are Java tabs, but also the fall-through case from above
-//    setToolTipText(null);
-    return super.getToolTipText(event);
-  }
-  */
-
-
   // TweakMode code
 	protected int horizontalAdjustment = 0;
 
diff --git a/java/src/processing/mode/java/pdex/PDEX.java b/java/src/processing/mode/java/pdex/PDEX.java
index d9ac64668..1e9dae51a 100644
--- a/java/src/processing/mode/java/pdex/PDEX.java
+++ b/java/src/processing/mode/java/pdex/PDEX.java
@@ -1,5 +1,9 @@
 package processing.mode.java.pdex;
 
+import com.google.classpath.ClassPath;
+import com.google.classpath.RegExpResourceFilter;
+
+import org.eclipse.jdt.core.compiler.IProblem;
 import org.eclipse.jdt.core.dom.ASTNode;
 import org.eclipse.jdt.core.dom.ASTVisitor;
 import org.eclipse.jdt.core.dom.CompilationUnit;
@@ -27,7 +31,12 @@ import java.util.Comparator;
 import java.util.Deque;
 import java.util.List;
 import java.util.Map;
+import java.util.concurrent.Executors;
+import java.util.concurrent.ScheduledExecutorService;
+import java.util.concurrent.ScheduledFuture;
+import java.util.concurrent.TimeUnit;
 import java.util.function.Consumer;
+import java.util.regex.Pattern;
 import java.util.stream.Collectors;
 
 import javax.swing.BorderFactory;
@@ -48,10 +57,12 @@ import javax.swing.tree.DefaultTreeModel;
 import javax.swing.tree.TreeModel;
 
 import processing.app.Messages;
+import processing.app.Preferences;
 import processing.app.Sketch;
 import processing.app.ui.EditorStatus;
 import processing.app.ui.Toolkit;
 import processing.mode.java.JavaEditor;
+import processing.mode.java.JavaMode;
 import processing.mode.java.pdex.PreprocessedSketch.SketchInterval;
 
 import static processing.mode.java.pdex.ASTUtils.*;
@@ -62,24 +73,28 @@ public class PDEX {
 
   private boolean enabled = true;
 
+  private ErrorChecker errorChecker;
+
   private ShowUsage showUsage;
   private Rename rename;
   private DebugTree debugTree;
 
   private JavaEditor editor;
-  private ErrorCheckerService ecs;
+  private PreprocessingService pps;
 
 
-  public PDEX(JavaEditor editor, ErrorCheckerService ecs) {
+  public PDEX(JavaEditor editor, PreprocessingService pps) {
     this.editor = editor;
-    this.ecs = ecs;
+    this.pps = pps;
 
     this.enabled = !editor.hasJavaTabs();
 
-    showUsage = new ShowUsage(editor, ecs);
+    errorChecker = new ErrorChecker(editor, pps);
+
+    showUsage = new ShowUsage(editor, pps);
     rename = new Rename(editor);
     if (SHOW_DEBUG_TREE) {
-      debugTree = new DebugTree(editor, ecs);
+      debugTree = new DebugTree(editor, pps);
     }
   }
 
@@ -87,21 +102,21 @@ public class PDEX {
   public void handleShowUsage(int tabIndex, int startTabOffset, int stopTabOffset) {
     Messages.log("* handleShowUsage");
     if (!enabled) return; // show usage disabled if java tabs
-    ecs.acceptWhenDone(ps -> showUsage.findUsageAndUpdateTree(ps, tabIndex, startTabOffset, stopTabOffset));
+    pps.whenDone(ps -> showUsage.findUsageAndUpdateTree(ps, tabIndex, startTabOffset, stopTabOffset));
   }
 
 
   public void handleRename(int tabIndex, int startTabOffset, int stopTabOffset) {
     Messages.log("* handleRename");
     if (!enabled) return;  // refactoring disabled w/ java tabs
-    ecs.acceptWhenDone(ps -> rename.handleRename(ps, tabIndex, startTabOffset, stopTabOffset));
+    pps.whenDone(ps -> rename.handleRename(ps, tabIndex, startTabOffset, stopTabOffset));
   }
 
 
   public void handleCtrlClick(int tabIndex, int offset) {
     Messages.log("* handleCtrlClick");
     if (!enabled) return;  // disabled w/ java tabs
-    ecs.acceptWhenDone(ps -> handleCtrlClick(ps, tabIndex, offset));
+    pps.whenDone(ps -> handleCtrlClick(ps, tabIndex, offset));
   }
 
 
@@ -113,7 +128,13 @@ public class PDEX {
   }
 
 
+  public void notifySketchChanged() {
+    errorChecker.notifySketchChanged();
+  }
+
+
   public void dispose() {
+    errorChecker.dispose();
     showUsage.dispose();
     rename.dispose();
     if (debugTree != null) {
@@ -178,16 +199,16 @@ public class PDEX {
     final JTree tree;
 
     final JavaEditor editor;
-    final ErrorCheckerService ecs;
+    final PreprocessingService pps;
 
     final Consumer<PreprocessedSketch> reloadListener;
 
     IBinding binding;
 
 
-    ShowUsage(JavaEditor editor, ErrorCheckerService ecs) {
+    ShowUsage(JavaEditor editor, PreprocessingService pps) {
       this.editor = editor;
-      this.ecs = ecs;
+      this.pps = pps;
 
       reloadListener = this::reloadShowUsage;
 
@@ -201,12 +222,12 @@ public class PDEX {
             // Delete references to ASTNodes so that whole AST can be GC'd
             binding = null;
             tree.setModel(null);
-            ecs.unregisterDoneListener(reloadListener);
+            pps.unregisterListener(reloadListener);
           }
 
           @Override
           public void componentShown(ComponentEvent e) {
-            ecs.registerDoneListener(reloadListener);
+            pps.registerListener(reloadListener);
           }
         });
         window.setSize(300, 400);
@@ -689,7 +710,7 @@ public class PDEX {
     final Consumer<PreprocessedSketch> updateListener;
 
 
-    DebugTree(JavaEditor editor, ErrorCheckerService ecs) {
+    DebugTree(JavaEditor editor, PreprocessingService pps) {
       updateListener = this::buildAndUpdateTree;
 
       window = new JDialog(editor);
@@ -713,7 +734,7 @@ public class PDEX {
       window.addComponentListener(new ComponentAdapter() {
         @Override
         public void componentHidden(ComponentEvent e) {
-          ecs.unregisterDoneListener(updateListener);
+          pps.unregisterListener(updateListener);
           tree.setModel(null);
         }
       });
@@ -723,8 +744,8 @@ public class PDEX {
       JScrollPane sp = new JScrollPane();
       sp.setViewportView(tree);
       window.add(sp);
-      ecs.acceptWhenDone(updateListener);
-      ecs.registerDoneListener(updateListener);
+      pps.whenDone(updateListener);
+      pps.registerListener(updateListener);
 
 
       tree.addTreeSelectionListener(e -> {
@@ -735,7 +756,7 @@ public class PDEX {
             (DefaultMutableTreeNode) tree.getLastSelectedPathComponent();
         if (tnode.getUserObject() instanceof ASTNode) {
           ASTNode node = (ASTNode) tnode.getUserObject();
-          ecs.acceptWhenDone(ps -> {
+          pps.whenDone(ps -> {
             SketchInterval si = ps.mapJavaToSketch(node);
             EventQueue.invokeLater(() -> {
               editor.highlight(si.tabIndex, si.startTabOffset, si.stopTabOffset);
@@ -797,4 +818,134 @@ public class PDEX {
 
   }
 
+
+
+  private static class ErrorChecker {
+
+    // Delay delivering error check result after last sketch change #2677
+    private final static long DELAY_BEFORE_UPDATE = 650;
+
+    private ScheduledExecutorService scheduler;
+    private volatile ScheduledFuture<?> scheduledUiUpdate = null;
+    private volatile long nextUiUpdate = 0;
+
+    private final Consumer<PreprocessedSketch> errorHandlerListener = this::handleSketchProblems;
+
+    private JavaEditor editor;
+
+
+    public ErrorChecker(JavaEditor editor, PreprocessingService pps) {
+      this.editor = editor;
+      scheduler = Executors.newSingleThreadScheduledExecutor();
+      pps.registerListener(errorHandlerListener);
+    }
+
+
+    public void notifySketchChanged() {
+      nextUiUpdate = System.currentTimeMillis() + DELAY_BEFORE_UPDATE;
+    }
+
+
+    public void dispose() {
+      if (scheduler != null) {
+        scheduler.shutdownNow();
+      }
+    }
+
+
+    private void handleSketchProblems(PreprocessedSketch ps) {
+      // Process problems
+      final List<Problem> problems = ps.problems.stream()
+          // Filter Warnings if they are not enabled
+          .filter(iproblem -> !(iproblem.isWarning() && !JavaMode.warningsEnabled))
+          // Hide a useless error which is produced when a line ends with
+          // an identifier without a semicolon. "Missing a semicolon" is
+          // also produced and is preferred over this one.
+          // (Syntax error, insert ":: IdentifierOrNew" to complete Expression)
+          // See: https://bugs.eclipse.org/bugs/show_bug.cgi?id=405780
+          .filter(iproblem -> !iproblem.getMessage()
+              .contains("Syntax error, insert \":: IdentifierOrNew\""))
+          // Transform into our Problems
+          .map(iproblem -> {
+            int start = iproblem.getSourceStart();
+            int stop = iproblem.getSourceEnd() + 1; // make it exclusive
+            SketchInterval in = ps.mapJavaToSketch(start, stop);
+            int line = ps.tabOffsetToTabLine(in.tabIndex, in.startTabOffset);
+            Problem p = new Problem(iproblem, in.tabIndex, line);
+            p.setPDEOffsets(in.startTabOffset, in.stopTabOffset);
+            return p;
+          })
+          .collect(Collectors.toList());
+
+      // Handle import suggestions
+      if (JavaMode.importSuggestEnabled) {
+        Map<String, List<Problem>> undefinedTypeProblems = problems.stream()
+            // Get only problems with undefined types/names
+            .filter(p -> {
+              int id = p.getIProblem().getID();
+              return id == IProblem.UndefinedType ||
+                  id == IProblem.UndefinedName ||
+                  id == IProblem.UnresolvedVariable;
+            })
+            // Group problems by the missing type/name
+            .collect(Collectors.groupingBy(p -> p.getIProblem().getArguments()[0]));
+
+        if (!undefinedTypeProblems.isEmpty()) {
+          final ClassPath cp = ps.searchClassPath;
+
+          // Get suggestions for each missing type, update the problems
+          undefinedTypeProblems.entrySet().stream()
+              .forEach(entry -> {
+                String missingClass = entry.getKey();
+                List<Problem> affectedProblems = entry.getValue();
+                String[] suggestions = getImportSuggestions(cp, missingClass);
+                affectedProblems.forEach(p -> p.setImportSuggestions(suggestions));
+              });
+        }
+      }
+
+      if (scheduledUiUpdate != null) {
+        scheduledUiUpdate.cancel(true);
+      }
+      // Update UI after a delay. See #2677
+      long delay = nextUiUpdate - System.currentTimeMillis();
+      Runnable uiUpdater = () -> {
+        if (nextUiUpdate > 0 && System.currentTimeMillis() >= nextUiUpdate) {
+          EventQueue.invokeLater(() -> editor.setProblemList(problems));
+        }
+      };
+      scheduledUiUpdate = scheduler.schedule(uiUpdater, delay,
+                                             TimeUnit.MILLISECONDS);
+    }
+
+
+    public static String[] getImportSuggestions(ClassPath cp, String className) {
+      RegExpResourceFilter regf = new RegExpResourceFilter(
+          Pattern.compile(".*"),
+          Pattern.compile("(.*\\$)?" + className + "\\.class",
+                          Pattern.CASE_INSENSITIVE));
+
+      String[] resources = cp.findResources("", regf);
+      return Arrays.stream(resources)
+          // remove ".class" suffix
+          .map(res -> res.substring(0, res.length() - 6))
+          // replace path separators with dots
+          .map(res -> res.replace('/', '.'))
+          // replace inner class separators with dots
+          .map(res -> res.replace('$', '.'))
+          // sort, prioritize clases from java. package
+          .sorted((o1, o2) -> {
+            // put java.* first, should be prioritized more
+            boolean o1StartsWithJava = o1.startsWith("java");
+            boolean o2StartsWithJava = o2.startsWith("java");
+            if (o1StartsWithJava != o2StartsWithJava) {
+              if (o1StartsWithJava) return -1;
+              return 1;
+            }
+            return o1.compareTo(o2);
+          })
+          .toArray(String[]::new);
+    }
+
+  }
 }
diff --git a/java/src/processing/mode/java/pdex/ErrorCheckerService.java b/java/src/processing/mode/java/pdex/PreprocessingService.java
similarity index 66%
rename from java/src/processing/mode/java/pdex/ErrorCheckerService.java
rename to java/src/processing/mode/java/pdex/PreprocessingService.java
index df5c0e764..34da90203 100644
--- a/java/src/processing/mode/java/pdex/ErrorCheckerService.java
+++ b/java/src/processing/mode/java/pdex/PreprocessingService.java
@@ -20,11 +20,8 @@ along with this program; if not, write to the Free Software Foundation, Inc.
 
 package processing.mode.java.pdex;
 
-import com.google.classpath.ClassPath;
 import com.google.classpath.ClassPathFactory;
-import com.google.classpath.RegExpResourceFilter;
 
-import java.awt.EventQueue;
 import java.io.File;
 import java.net.MalformedURLException;
 import java.net.URL;
@@ -41,21 +38,12 @@ import java.util.concurrent.ArrayBlockingQueue;
 import java.util.concurrent.BlockingQueue;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.CopyOnWriteArraySet;
-import java.util.concurrent.Executors;
-import java.util.concurrent.ScheduledExecutorService;
-import java.util.concurrent.ScheduledFuture;
-import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.function.Consumer;
-import java.util.regex.Pattern;
 import java.util.stream.Collectors;
-import java.util.stream.Stream;
 import java.util.stream.StreamSupport;
 
-import javax.swing.event.DocumentEvent;
-import javax.swing.event.DocumentListener;
 import javax.swing.text.BadLocationException;
-import javax.swing.text.Document;
 
 import org.eclipse.jdt.core.JavaCore;
 import org.eclipse.jdt.core.compiler.IProblem;
@@ -65,7 +53,6 @@ import org.eclipse.jdt.core.dom.CompilationUnit;
 
 import processing.app.Library;
 import processing.app.Messages;
-import processing.app.Preferences;
 import processing.app.Sketch;
 import processing.app.SketchCode;
 import processing.app.SketchException;
@@ -74,7 +61,6 @@ import processing.data.IntList;
 import processing.data.StringList;
 import processing.mode.java.JavaEditor;
 import processing.mode.java.JavaMode;
-import processing.mode.java.pdex.PreprocessedSketch.SketchInterval;
 import processing.mode.java.pdex.TextTransform.OffsetMapper;
 import processing.mode.java.preproc.PdePreprocessor;
 import processing.mode.java.preproc.PdePreprocessor.Mode;
@@ -84,39 +70,23 @@ import processing.mode.java.preproc.PdePreprocessor.Mode;
  * The main error checking service
  */
 @SuppressWarnings("unchecked")
-public class ErrorCheckerService {
+public class PreprocessingService {
 
   protected final JavaEditor editor;
 
-  /** The amazing eclipse ast parser */
   protected final ASTParser parser = ASTParser.newParser(AST.JLS8);
 
-  /** Class path factory for ASTGenerator */
-  protected final ClassPathFactory classPathFactory = new ClassPathFactory();
+  private final ClassPathFactory classPathFactory = new ClassPathFactory();
 
-  /**
-   * Used to indirectly stop the Error Checker Thread
-   */
-  private volatile boolean running;
-
-  /**
-   * Error checking doesn't happen before this interval has ellapsed since the
-   * last request() call.
-   */
-  private final static long errorCheckInterval = 650;
-
-  private Thread errorCheckerThread;
+  private final Thread preprocessingThread;
   private final BlockingQueue<Boolean> requestQueue = new ArrayBlockingQueue<>(1);
-  private ScheduledExecutorService scheduler;
-  private volatile ScheduledFuture<?> scheduledUiUpdate = null;
-  private volatile long nextUiUpdate = 0;
 
   private final Object requestLock = new Object();
-  private boolean needsCheck = false;
 
-  private AtomicBoolean codeFolderChanged = new AtomicBoolean(true);
-  private AtomicBoolean librariesChanged = new AtomicBoolean(true);
+  private final AtomicBoolean codeFolderChanged = new AtomicBoolean(true);
+  private final AtomicBoolean librariesChanged = new AtomicBoolean(true);
 
+  private volatile boolean running;
   private CompletableFuture<PreprocessedSketch> preprocessingTask = new CompletableFuture<>();
 
   private CompletableFuture<?> lastCallback =
@@ -124,75 +94,58 @@ public class ErrorCheckerService {
         complete(null); // initialization block
       }};
 
-  private final Consumer<PreprocessedSketch> errorHandlerListener = this::handleSketchProblems;
-
   private volatile boolean isEnabled = true;
-  private volatile boolean isContinuousCheckEnabled = true;
 
 
-  public ErrorCheckerService(JavaEditor editor) {
+  public PreprocessingService(JavaEditor editor) {
     this.editor = editor;
     isEnabled = !editor.hasJavaTabs();
-    isContinuousCheckEnabled = JavaMode.errorCheckEnabled;
-    registerDoneListener(errorHandlerListener);
+
+    preprocessingThread = new Thread(this::mainLoop, "ECS");
+    preprocessingThread.start();
   }
 
 
   private void mainLoop() {
     running = true;
     PreprocessedSketch prevResult = null;
+    Messages.log("PPS: Hi!");
     while (running) {
       try {
         try {
-          requestQueue.take(); // blocking until check requested
+          requestQueue.take(); // blocking until requested
         } catch (InterruptedException e) {
           running = false;
           break;
         }
 
-        Messages.log("Starting preprocessing");
+        Messages.log("PPS: Starting");
 
         prevResult = preprocessSketch(prevResult);
 
         synchronized (requestLock) {
           if (requestQueue.isEmpty()) {
-            Messages.log("Completing preprocessing");
+            Messages.log("PPS: Completed");
             preprocessingTask.complete(prevResult);
           }
         }
       } catch (Exception e) {
-        Messages.loge("problem in error checker loop", e);
+        Messages.loge("problem in preprocessor service loop", e);
       }
     }
+    Messages.log("PPS: Bye!");
   }
 
 
-  public void start() {
-    scheduler = Executors.newSingleThreadScheduledExecutor();
-    errorCheckerThread = new Thread(this::mainLoop, "ECS");
-    errorCheckerThread.start();
-  }
-
-
-  public void stop() {
+  public void dispose() {
     cancel();
     running = false;
-    if (errorCheckerThread != null) {
-      running = false;
-      errorCheckerThread.interrupt();
-    }
-    if (scheduler != null) {
-      scheduler.shutdownNow();
-    }
+    preprocessingThread.interrupt();
   }
 
 
   public void cancel() {
     requestQueue.clear();
-    nextUiUpdate = 0;
-    if (scheduledUiUpdate != null) {
-      scheduledUiUpdate.cancel(true);
-    }
   }
 
 
@@ -202,35 +155,28 @@ public class ErrorCheckerService {
       if (preprocessingTask.isDone()) {
         preprocessingTask = new CompletableFuture<>();
         // Register callback which executes all listeners
-        registerCallback(this::fireDoneListeners);
-      }
-      if (isContinuousCheckEnabled) {
-        // Continuous check enabled, request
-        nextUiUpdate = System.currentTimeMillis() + errorCheckInterval;
-        requestQueue.offer(Boolean.TRUE);
-      } else {
-        // Continuous check not enabled, take note
-        needsCheck = true;
+        whenDone(this::fireListeners);
       }
+      requestQueue.offer(Boolean.TRUE);
     }
   }
 
 
   public void notifyLibrariesChanged() {
+    Messages.log("PPS: notified libraries changed");
     librariesChanged.set(true);
-    Messages.log("Notify libraries changed");
     notifySketchChanged();
   }
 
 
   public void notifyCodeFolderChanged() {
+    Messages.log("PPS: snotified code folder changed");
     codeFolderChanged.set(true);
-    Messages.log("Notify code folder changed");
     notifySketchChanged();
   }
 
 
-  private void registerCallback(Consumer<PreprocessedSketch> callback) {
+  public void whenDone(Consumer<PreprocessedSketch> callback) {
     if (!isEnabled) return;
     synchronized (requestLock) {
       lastCallback = preprocessingTask
@@ -238,49 +184,36 @@ public class ErrorCheckerService {
           .thenAcceptBothAsync(lastCallback, (ps, a) -> callback.accept(ps))
           // Make sure exception in callback won't cancel whole callback chain
           .handleAsync((res, e) -> {
-            if (e != null) Messages.loge("problem during preprocessing callback", e);
+            if (e != null) Messages.loge("exception in preprocessing callback", e);
             return res;
           });
     }
   }
 
 
-  public void acceptWhenDone(Consumer<PreprocessedSketch> callback) {
-    if (!isEnabled) return;
-    synchronized (requestLock) {
-      // Continuous check not enabled, request check now
-      if (needsCheck && !isContinuousCheckEnabled) {
-        needsCheck = false;
-        requestQueue.offer(Boolean.TRUE);
-      }
-      registerCallback(callback);
-    }
-  }
-
-
 
   /// LISTENERS ----------------------------------------------------------------
 
 
-  private Set<Consumer<PreprocessedSketch>> doneListeners = new CopyOnWriteArraySet<>();
+  private Set<Consumer<PreprocessedSketch>> listeners = new CopyOnWriteArraySet<>();
 
 
-  public void registerDoneListener(Consumer<PreprocessedSketch> listener) {
-    if (listener != null) doneListeners.add(listener);
+  public void registerListener(Consumer<PreprocessedSketch> listener) {
+    if (listener != null) listeners.add(listener);
   }
 
 
-  public void unregisterDoneListener(Consumer<PreprocessedSketch> listener) {
-    doneListeners.remove(listener);
+  public void unregisterListener(Consumer<PreprocessedSketch> listener) {
+    listeners.remove(listener);
   }
 
 
-  private void fireDoneListeners(PreprocessedSketch ps) {
-    for (Consumer<PreprocessedSketch> listener : doneListeners) {
+  private void fireListeners(PreprocessedSketch ps) {
+    for (Consumer<PreprocessedSketch> listener : listeners) {
       try {
         listener.accept(ps);
       } catch (Exception e) {
-        Messages.loge("error when firing ecs listener", e);
+        Messages.loge("error when firing preprocessing listener", e);
       }
     }
   }
@@ -289,30 +222,6 @@ public class ErrorCheckerService {
   /// --------------------------------------------------------------------------
 
 
-
-  public void addDocumentListener(Document doc) {
-    if (doc != null) doc.addDocumentListener(sketchChangedListener);
-  }
-
-
-  protected final DocumentListener sketchChangedListener = new DocumentListener() {
-    @Override
-    public void insertUpdate(DocumentEvent e) {
-      notifySketchChanged();
-    }
-
-    @Override
-    public void removeUpdate(DocumentEvent e) {
-      notifySketchChanged();
-    }
-
-    @Override
-    public void changedUpdate(DocumentEvent e) {
-      notifySketchChanged();
-    }
-  };
-
-
   private PreprocessedSketch preprocessSketch(PreprocessedSketch prevResult) {
 
     boolean firstCheck = prevResult == null;
@@ -505,77 +414,6 @@ public class ErrorCheckerService {
   }
 
 
-  private void handleSketchProblems(PreprocessedSketch ps) {
-    // Process problems
-    final List<Problem> problems = ps.problems.stream()
-        // Filter Warnings if they are not enabled
-        .filter(iproblem -> !(iproblem.isWarning() && !JavaMode.warningsEnabled))
-        // Hide a useless error which is produced when a line ends with
-        // an identifier without a semicolon. "Missing a semicolon" is
-        // also produced and is preferred over this one.
-        // (Syntax error, insert ":: IdentifierOrNew" to complete Expression)
-        // See: https://bugs.eclipse.org/bugs/show_bug.cgi?id=405780
-        .filter(iproblem -> !iproblem.getMessage()
-            .contains("Syntax error, insert \":: IdentifierOrNew\""))
-        // Transform into our Problems
-        .map(iproblem -> {
-          int start = iproblem.getSourceStart();
-          int stop = iproblem.getSourceEnd() + 1; // make it exclusive
-          SketchInterval in = ps.mapJavaToSketch(start, stop);
-          int line = ps.tabOffsetToTabLine(in.tabIndex, in.startTabOffset);
-          Problem p = new Problem(iproblem, in.tabIndex, line);
-          p.setPDEOffsets(in.startTabOffset, in.stopTabOffset);
-          return p;
-        })
-        .collect(Collectors.toList());
-
-    // Handle import suggestions
-    if (Preferences.getBoolean(JavaMode.SUGGEST_IMPORTS_PREF)) {
-      Map<String, List<Problem>> undefinedTypeProblems = problems.stream()
-          // Get only problems with undefined types/names
-          .filter(p -> {
-            int id = p.getIProblem().getID();
-            return id == IProblem.UndefinedType ||
-                id == IProblem.UndefinedName ||
-                id == IProblem.UnresolvedVariable;
-          })
-          // Group problems by the missing type/name
-          .collect(Collectors.groupingBy(p -> p.getIProblem().getArguments()[0]));
-
-      if (!undefinedTypeProblems.isEmpty()) {
-        final ClassPath cp = ps.searchClassPath;
-
-        // Get suggestions for each missing type, update the problems
-        undefinedTypeProblems.entrySet().stream()
-            .forEach(entry -> {
-              String missingClass = entry.getKey();
-              List<Problem> affectedProblems = entry.getValue();
-              String[] suggestions = getImportSuggestions(cp, missingClass);
-              affectedProblems.forEach(p -> p.setImportSuggestions(suggestions));
-            });
-      }
-    }
-
-    if (scheduledUiUpdate != null) {
-      scheduledUiUpdate.cancel(true);
-    }
-    // Update UI after a delay. See #2677
-    long delay = nextUiUpdate - System.currentTimeMillis();
-    Runnable uiUpdater = () -> {
-      if (nextUiUpdate > 0 && System.currentTimeMillis() >= nextUiUpdate) {
-        EventQueue.invokeLater(() -> {
-          if (isContinuousCheckEnabled) {
-            editor.setProblemList(problems);
-          }
-        });
-      }
-    };
-    scheduledUiUpdate = scheduler.schedule(uiUpdater, delay,
-                                           TimeUnit.MILLISECONDS);
-  }
-
-
-
   /// IMPORTS -----------------------------------------------------------------
 
   private List<ImportStatement> coreAndDefaultImports;
@@ -608,6 +446,22 @@ public class ErrorCheckerService {
   }
 
 
+  private static boolean checkIfImportsChanged(List<ImportStatement> prevImports,
+                                                 List<ImportStatement> imports) {
+    if (imports.size() != prevImports.size()) {
+      return true;
+    } else {
+      int count = imports.size();
+      for (int i = 0; i < count; i++) {
+        if (!imports.get(i).isSameAs(prevImports.get(i))) {
+          return true;
+        }
+      }
+    }
+    return false;
+  }
+
+
 
   /// CLASSPATHS ---------------------------------------------------------------
 
@@ -621,8 +475,8 @@ public class ErrorCheckerService {
 
   private List<String> codeFolderClassPath;
 
-  private List<String> searchLibraryClassPath;
   private List<String> sketchLibraryClassPath;
+  private List<String> searchLibraryClassPath;
 
 
   private static List<String> buildCodeFolderClassPath(Sketch sketch) {
@@ -670,6 +524,7 @@ public class ErrorCheckerService {
     return sanitizeClassPath(classPath.toString());
   }
 
+
   private static List<String> buildSearchLibraryClassPath(JavaMode mode) {
     StringBuilder classPath = new StringBuilder();
 
@@ -735,36 +590,7 @@ public class ErrorCheckerService {
 
 
 
-  public static String[] getImportSuggestions(ClassPath cp, String className) {
-    RegExpResourceFilter regf = new RegExpResourceFilter(
-        Pattern.compile(".*"),
-        Pattern.compile("(.*\\$)?" + className + "\\.class",
-                        Pattern.CASE_INSENSITIVE));
-
-    String[] resources = cp.findResources("", regf);
-    return Arrays.stream(resources)
-        // remove ".class" suffix
-        .map(res -> res.substring(0, res.length() - 6))
-        // replace path separators with dots
-        .map(res -> res.replace('/', '.'))
-        // replace inner class separators with dots
-        .map(res -> res.replace('$', '.'))
-        // sort, prioritize clases from java. package
-        .sorted((o1, o2) -> {
-          // put java.* first, should be prioritized more
-          boolean o1StartsWithJava = o1.startsWith("java");
-          boolean o2StartsWithJava = o2.startsWith("java");
-          if (o1StartsWithJava != o2StartsWithJava) {
-            if (o1StartsWithJava) return -1;
-            return 1;
-          }
-          return o1.compareTo(o2);
-        })
-        .toArray(String[]::new);
-  }
-
-
-  protected static CompilationUnit makeAST(ASTParser parser,
+  private static CompilationUnit makeAST(ASTParser parser,
                                            char[] source,
                                            Map<String, String> options) {
     parser.setSource(source);
@@ -776,7 +602,7 @@ public class ErrorCheckerService {
   }
 
 
-  protected static CompilationUnit makeASTWithBindings(ASTParser parser,
+  private static CompilationUnit makeASTWithBindings(ASTParser parser,
                                                        char[] source,
                                                        Map<String, String> options,
                                                        String className,
@@ -796,47 +622,12 @@ public class ErrorCheckerService {
   /**
    * Ignore processing packages, java.*.*. etc.
    */
-  protected boolean ignorableImport(String packageName) {
+  private boolean ignorableImport(String packageName) {
     return (packageName.startsWith("java.") ||
             packageName.startsWith("javax."));
   }
 
 
-  protected static boolean ignorableSuggestionImport(PreprocessedSketch ps, String impName) {
-
-    String impNameLc = impName.toLowerCase();
-
-    List<ImportStatement> programImports = ps.programImports;
-    List<ImportStatement> codeFolderImports = ps.codeFolderImports;
-
-    boolean isImported = Stream
-        .concat(programImports.stream(), codeFolderImports.stream())
-        .anyMatch(impS -> {
-          String packageNameLc = impS.getPackageName().toLowerCase();
-          return impNameLc.startsWith(packageNameLc);
-        });
-
-    if (isImported) return false;
-
-    final String include = "include";
-    final String exclude = "exclude";
-
-    if (impName.startsWith("processing")) {
-      if (JavaMode.suggestionsMap.containsKey(include) && JavaMode.suggestionsMap.get(include).contains(impName)) {
-        return false;
-      } else if (JavaMode.suggestionsMap.containsKey(exclude) && JavaMode.suggestionsMap.get(exclude).contains(impName)) {
-        return true;
-      }
-    } else if (impName.startsWith("java")) {
-      if (JavaMode.suggestionsMap.containsKey(include) && JavaMode.suggestionsMap.get(include).contains(impName)) {
-        return false;
-      }
-    }
-
-    return true;
-  }
-
-
   static private final Map<String, String> COMPILER_OPTIONS;
   static {
     Map<String, String> compilerOptions = new HashMap<>();
@@ -879,37 +670,6 @@ public class ErrorCheckerService {
   }
 
 
-  /**
-   * Checks if import statements in the sketch have changed. If they have,
-   * compiler classpath needs to be updated.
-   */
-  protected static boolean checkIfImportsChanged(List<ImportStatement> prevImports,
-                                                 List<ImportStatement> imports) {
-    if (imports.size() != prevImports.size()) {
-      return true;
-    } else {
-      int count = imports.size();
-      for (int i = 0; i < count; i++) {
-        if (!imports.get(i).isSameAs(prevImports.get(i))) {
-          return true;
-        }
-      }
-    }
-    return false;
-  }
-
-
-  public void handlePreferencesChange() {
-    isContinuousCheckEnabled = JavaMode.errorCheckEnabled;
-    if (isContinuousCheckEnabled) {
-      Messages.log(editor.getSketch().getName() + " Error Checker enabled.");
-      notifySketchChanged();
-    } else {
-      Messages.log(editor.getSketch().getName() + " Error Checker disabled.");
-    }
-  }
-
-
   public void handleHasJavaTabsChange(boolean hasJavaTabs) {
     isEnabled = !hasJavaTabs;
     if (isEnabled) {