diff --git a/python/src/META-INF/python-plugin-common.xml b/python/src/META-INF/python-plugin-common.xml
index c847af453dee..ee41582fa341 100644
--- a/python/src/META-INF/python-plugin-common.xml
+++ b/python/src/META-INF/python-plugin-common.xml
@@ -116,6 +116,12 @@
     <runnableScriptFilter implementation="com.jetbrains.python.testing.PythonUnitTestRunnableScriptFilter"/>
   </extensions>
 
+  <project-components>
+    <component>
+      <implementation-class>com.jetbrains.python.PythonPsiManager</implementation-class>
+    </component>
+  </project-components>
+
   <actions>
     <action
         id="Devmode.DumpPsi"
diff --git a/python/src/com/jetbrains/python/PythonPsiManager.java b/python/src/com/jetbrains/python/PythonPsiManager.java
new file mode 100644
index 000000000000..8f2514db5179
--- /dev/null
+++ b/python/src/com/jetbrains/python/PythonPsiManager.java
@@ -0,0 +1,96 @@
+package com.jetbrains.python;
+
+import com.intellij.openapi.components.AbstractProjectComponent;
+import com.intellij.openapi.project.Project;
+import com.intellij.psi.PsiDirectory;
+import com.intellij.psi.PsiElement;
+import com.intellij.psi.PsiFile;
+import com.intellij.psi.PsiFileSystemItem;
+import com.intellij.psi.impl.PsiManagerImpl;
+import com.intellij.psi.impl.PsiModificationTrackerImpl;
+import com.intellij.psi.impl.PsiTreeChangeEventImpl;
+import com.intellij.psi.impl.PsiTreeChangePreprocessor;
+import com.jetbrains.python.psi.PyFile;
+import com.jetbrains.python.psi.PyFunction;
+
+/**
+ * @author yole
+ */
+public class PythonPsiManager extends AbstractProjectComponent implements PsiTreeChangePreprocessor {
+  private final PsiManagerImpl myPsiManager;
+  private PsiModificationTrackerImpl myModificationTracker;
+
+  public PythonPsiManager(Project project, PsiManagerImpl psiManager) {
+    super(project);
+    myPsiManager = psiManager;
+  }
+
+  public void initComponent() {
+    myModificationTracker = (PsiModificationTrackerImpl) myPsiManager.getModificationTracker();
+    myPsiManager.addTreeChangePreprocessor(this);
+  }
+
+  public void treeChanged(PsiTreeChangeEventImpl event) {
+    boolean changedInsideCodeBlock = false;
+
+    switch (event.getCode()) {
+      case BEFORE_CHILDREN_CHANGE:
+        if (event.getParent() instanceof PsiFile) {
+          changedInsideCodeBlock = true;
+          break; // May be caused by fake PSI event from PomTransaction. A real event will anyway follow.
+        }
+
+      case CHILDREN_CHANGED :
+        changedInsideCodeBlock = isInsideCodeBlock(event.getParent());
+      break;
+
+      case BEFORE_CHILD_ADDITION:
+      case BEFORE_CHILD_REMOVAL:
+      case CHILD_ADDED :
+      case CHILD_REMOVED :
+        changedInsideCodeBlock = isInsideCodeBlock(event.getParent());
+      break;
+
+      case BEFORE_PROPERTY_CHANGE:
+      case PROPERTY_CHANGED :
+        changedInsideCodeBlock = false;
+      break;
+
+      case BEFORE_CHILD_REPLACEMENT:
+      case CHILD_REPLACED :
+        changedInsideCodeBlock = isInsideCodeBlock(event.getParent());
+      break;
+
+      case BEFORE_CHILD_MOVEMENT:
+      case CHILD_MOVED :
+        changedInsideCodeBlock = isInsideCodeBlock(event.getOldParent()) && isInsideCodeBlock(event.getNewParent());
+      break;
+    }
+
+    if (!changedInsideCodeBlock) {
+      myModificationTracker.incOutOfCodeBlockModificationCounter();
+    }
+  }
+
+  private static boolean isInsideCodeBlock(PsiElement element) {
+    if (element instanceof PsiFileSystemItem) {
+      return false;
+    }
+
+    if (element == null || element.getParent() == null) return true;
+
+    while(true) {
+      if (element instanceof PyFile) {
+        return false;
+      }
+      if (element instanceof PsiFile || element instanceof PsiDirectory || element == null) {
+        return true;
+      }
+      PsiElement pparent = element.getParent();
+      if (pparent instanceof PyFunction) {
+        return true;
+      }
+      element = pparent;
+    }
+  }
+}