diff --git a/plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/META-INF/InspectionGadgets.xml b/plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/META-INF/InspectionGadgets.xml
index 1ca82904785d..18654c807735 100644
--- a/plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/META-INF/InspectionGadgets.xml
+++ b/plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/META-INF/InspectionGadgets.xml
@@ -2388,6 +2388,10 @@
                      key="size.replaceable.by.isempty.display.name" groupBundle="messages.InspectionsBundle"
                      groupKey="group.names.code.style.issues" enabledByDefault="false" level="WARNING"
                      implementationClass="com.siyeh.ig.style.SizeReplaceableByIsEmptyInspection"/>
+    <localInspection language="JAVA" shortName="ProblematicWhitespace" bundle="com.siyeh.InspectionGadgetsBundle"
+                     key="problematic.whitespace.display.name" groupBundle="messages.InspectionsBundle"
+                     groupKey="group.names.code.style.issues" enabledByDefault="false" level="WARNING"
+                     implementationClass="com.siyeh.ig.style.ProblematicWhitespaceInspection"/>
 
     <!--group.names.threading.issues-->
     <localInspection language="JAVA" suppressId="AccessToNonThreadSafeStaticField" shortName="AccessToNonThreadSafeStaticFieldFromInstance"
diff --git a/plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/InspectionGadgetsBundle.properties b/plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/InspectionGadgetsBundle.properties
index 1f3e7e82dcd1..cb1b9cd30505 100644
--- a/plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/InspectionGadgetsBundle.properties
+++ b/plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/InspectionGadgetsBundle.properties
@@ -2053,3 +2053,7 @@ package.info.without.package.family.quickfix=add package statement
 auto.closeable.resource.display.name=AutoCloseable used without 'try'-with-resources
 auto.closeable.resource.problem.descriptor=''{0}'' used without ''try''-with-resources statement
 auto.closeable.resource.returned.option=Ignore AutoCloseable instances returned from method calls
+problematic.whitespace.display.name=Problematic whitespace
+problematic.whitespace.tabs.problem.descriptor=File ''{0}'' uses tabs for indentation
+problematic.whitespace.spaces.problem.descriptor=File ''{0}'' uses spaces for indentation
+problematic.whitespace.show.whitespaces.quickfix=Toggle show whitespace in the editor
\ No newline at end of file
diff --git a/plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/BaseInspectionVisitor.java b/plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/BaseInspectionVisitor.java
index 028b3591837f..1ba34a6235d8 100644
--- a/plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/BaseInspectionVisitor.java
+++ b/plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/BaseInspectionVisitor.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2003-2012 Dave Griffith, Bas Leijdekkers
+ * Copyright 2003-2013 Dave Griffith, Bas Leijdekkers
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -222,17 +222,10 @@ public abstract class BaseInspectionVisitor extends JavaElementVisitor {
   }
 
   @Override
-  public void visitReferenceExpression(
-    PsiReferenceExpression expression) {
+  public void visitReferenceExpression(PsiReferenceExpression expression) {
     visitExpression(expression);
   }
 
-  @Override
-  public final void visitWhiteSpace(PsiWhiteSpace space) {
-    // none of our inspections need to do anything with white space,
-    // so this is a performance optimization
-  }
-
   public final void setProblemsHolder(ProblemsHolder holder) {
     this.holder = holder;
   }
diff --git a/plugins/InspectionGadgets/src/com/siyeh/ig/style/ProblematicWhitespaceInspection.java b/plugins/InspectionGadgets/src/com/siyeh/ig/style/ProblematicWhitespaceInspection.java
new file mode 100644
index 000000000000..8f823f019770
--- /dev/null
+++ b/plugins/InspectionGadgets/src/com/siyeh/ig/style/ProblematicWhitespaceInspection.java
@@ -0,0 +1,165 @@
+/*
+ * Copyright 2000-2013 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.siyeh.ig.style;
+
+import com.intellij.codeInspection.ProblemDescriptor;
+import com.intellij.ide.highlighter.JavaFileType;
+import com.intellij.openapi.editor.Document;
+import com.intellij.openapi.editor.Editor;
+import com.intellij.openapi.editor.EditorSettings;
+import com.intellij.openapi.fileEditor.FileEditorManager;
+import com.intellij.openapi.project.Project;
+import com.intellij.openapi.util.TextRange;
+import com.intellij.psi.PsiDocumentManager;
+import com.intellij.psi.PsiJavaFile;
+import com.intellij.psi.codeStyle.CodeStyleSettings;
+import com.intellij.psi.codeStyle.CodeStyleSettingsManager;
+import com.intellij.psi.codeStyle.CommonCodeStyleSettings;
+import com.siyeh.InspectionGadgetsBundle;
+import com.siyeh.ig.BaseInspection;
+import com.siyeh.ig.BaseInspectionVisitor;
+import com.siyeh.ig.InspectionGadgetsFix;
+import org.jetbrains.annotations.Nls;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+/**
+ * @author Bas Leijdekkers
+ */
+public class ProblematicWhitespaceInspection extends BaseInspection {
+
+  @Nls
+  @NotNull
+  @Override
+  public String getDisplayName() {
+    return InspectionGadgetsBundle.message("problematic.whitespace.display.name");
+  }
+
+  @NotNull
+  @Override
+  protected String buildErrorString(Object... infos) {
+    final Boolean useTabs = (Boolean)infos[2];
+    return useTabs.booleanValue()
+           ? InspectionGadgetsBundle.message("problematic.whitespace.spaces.problem.descriptor", (String)infos[0])
+           : InspectionGadgetsBundle.message("problematic.whitespace.tabs.problem.descriptor", (String)infos[0]);
+  }
+
+  @Nullable
+  @Override
+  protected InspectionGadgetsFix buildFix(Object... infos) {
+    final boolean buildFix = ((Boolean)infos[1]).booleanValue();
+    if (!buildFix) {
+      return null;
+    }
+    return new ShowWhitespaceFix();
+  }
+
+
+  private static class ShowWhitespaceFix extends InspectionGadgetsFix {
+
+    @NotNull
+    @Override
+    public String getName() {
+      return InspectionGadgetsBundle.message("problematic.whitespace.show.whitespaces.quickfix");
+    }
+
+    @NotNull
+    @Override
+    public String getFamilyName() {
+      return getName();
+    }
+
+    @Override
+    protected void doFix(Project project, ProblemDescriptor descriptor) {
+      final FileEditorManager editorManager = FileEditorManager.getInstance(project);
+      final Editor editor = editorManager.getSelectedTextEditor();
+      if (editor == null) {
+        return;
+      }
+      final EditorSettings settings = editor.getSettings();
+      settings.setWhitespacesShown(!settings.isWhitespacesShown());
+      editor.getComponent().repaint();
+    }
+  }
+
+
+  @Override
+  public BaseInspectionVisitor buildVisitor() {
+    return new ProblematicWhitespaceVisitor();
+  }
+
+  private static class ProblematicWhitespaceVisitor extends BaseInspectionVisitor {
+
+    @Override
+    public void visitJavaFile(PsiJavaFile file) {
+      super.visitJavaFile(file);
+      final CodeStyleSettings settings = CodeStyleSettingsManager.getSettings(file.getProject());
+      final CommonCodeStyleSettings.IndentOptions indentOptions = settings.getIndentOptions(JavaFileType.INSTANCE);
+      final boolean useTabs = indentOptions.USE_TAB_CHARACTER;
+      final boolean smartTabs = indentOptions.SMART_TABS;
+      final Document document = PsiDocumentManager.getInstance(file.getProject()).getDocument(file);
+      if (document == null) {
+        return;
+      }
+      final int lineCount = document.getLineCount();
+      int previousLineIndent = 0;
+      for (int i = 0; i < lineCount; i++) {
+        final int startOffset = document.getLineStartOffset(i);
+        final int endOffset = document.getLineEndOffset(i);
+        final String line = document.getText(new TextRange(startOffset, endOffset));
+        boolean spaceSeen = false;
+        for (int j = 0, length = line.length(); j < length; j++) {
+          final char c = line.charAt(j);
+          if (c == '\t') {
+            if (useTabs) {
+              if (smartTabs && spaceSeen) {
+                registerError(file, file.getName(), Boolean.valueOf(isOnTheFly()), Boolean.TRUE);
+                return;
+              }
+            }
+            else {
+              registerError(file, file.getName(), Boolean.valueOf(isOnTheFly()), Boolean.FALSE);
+              return;
+            }
+          }
+          else if (c == ' ') {
+            if (useTabs) {
+              if (!smartTabs) {
+                registerError(file, file.getName(), Boolean.valueOf(isOnTheFly()), Boolean.TRUE);
+                return;
+              }
+              else {
+                final int currentIndent = Math.max(0, j);
+                if (currentIndent != previousLineIndent) {
+                  registerError(file, file.getName(), Boolean.valueOf(isOnTheFly()), Boolean.TRUE);
+                  return;
+                }
+                previousLineIndent = currentIndent;
+              }
+            }
+            spaceSeen = true;
+          }
+          else {
+            if (!spaceSeen) {
+              previousLineIndent = Math.max(0, j);
+            }
+            break;
+          }
+        }
+      }
+    }
+  }
+}
diff --git a/plugins/InspectionGadgets/src/inspectionDescriptions/ProblematicWhitespace.html b/plugins/InspectionGadgets/src/inspectionDescriptions/ProblematicWhitespace.html
new file mode 100644
index 000000000000..f06337efebc2
--- /dev/null
+++ b/plugins/InspectionGadgets/src/inspectionDescriptions/ProblematicWhitespace.html
@@ -0,0 +1,10 @@
+<html>
+<body>
+Reports tabs used for indentation when the code style is configured to use only spaces. Reports spaces used for indentation when
+the code style is configured to use only tabs. Reports spaces used for indentation and tabs used for alignment when the code
+style is configured to use smart tabs.
+<!-- tooltip end -->
+<p>
+
+</body>
+</html>
\ No newline at end of file
diff --git a/plugins/InspectionGadgets/testsrc/com/siyeh/ig/style/ProblematicWhitespaceInspectionTest.java b/plugins/InspectionGadgets/testsrc/com/siyeh/ig/style/ProblematicWhitespaceInspectionTest.java
new file mode 100644
index 000000000000..c0e062c6d79b
--- /dev/null
+++ b/plugins/InspectionGadgets/testsrc/com/siyeh/ig/style/ProblematicWhitespaceInspectionTest.java
@@ -0,0 +1,76 @@
+/*
+ * Copyright 2000-2013 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.siyeh.ig.style;
+
+import com.intellij.codeInspection.InspectionProfileEntry;
+import com.intellij.ide.highlighter.JavaFileType;
+import com.intellij.psi.codeStyle.CodeStyleSettings;
+import com.intellij.psi.codeStyle.CodeStyleSettingsManager;
+import com.intellij.psi.codeStyle.CommonCodeStyleSettings;
+import com.siyeh.ig.LightInspectionTestCase;
+
+/**
+ * @author Bas Leijdekkers
+ */
+public class ProblematicWhitespaceInspectionTest extends LightInspectionTestCase {
+
+  public void testTabsInFile() {
+    final CodeStyleSettings settings = CodeStyleSettingsManager.getSettings(getProject());
+    settings.getIndentOptions(JavaFileType.INSTANCE).USE_TAB_CHARACTER = false;
+    doTest("/*File 'X.java' uses tabs for indentation*/class X {\n" +
+           "\tString s;\n" +
+           "}\n/**/");
+  }
+
+  public void testTabsInFile2() {
+    final CodeStyleSettings settings = CodeStyleSettingsManager.getSettings(getProject());
+    settings.getIndentOptions(JavaFileType.INSTANCE).USE_TAB_CHARACTER = true;
+    doTest("class X {\n" +
+           "\tString s;\n" +
+           "}\n");
+  }
+
+  public void testSpacesInFile() {
+    final CodeStyleSettings settings = CodeStyleSettingsManager.getSettings(getProject());
+    settings.getIndentOptions(JavaFileType.INSTANCE).USE_TAB_CHARACTER = true;
+    doTest("/*File 'X.java' uses spaces for indentation*/class X {\n" +
+           "  String s;\n" +
+           "}\n/**/");
+  }
+
+  public void testSpacesInFile2() {
+    final CodeStyleSettings settings = CodeStyleSettingsManager.getSettings(getProject());
+    settings.getIndentOptions(JavaFileType.INSTANCE).USE_TAB_CHARACTER = false;
+    doTest("class X {\n" +
+           "  String s;\n" +
+           "}\n");
+  }
+
+  public void testSmartTabsInFile() {
+    final CodeStyleSettings settings = CodeStyleSettingsManager.getSettings(getProject());
+    final CommonCodeStyleSettings.IndentOptions options = settings.getIndentOptions(JavaFileType.INSTANCE);
+    options.USE_TAB_CHARACTER = true;
+    options.SMART_TABS = true;
+    doTest("/*File 'X.java' uses spaces for indentation*/class X {\n" +
+           "  \tString s;\n" +
+           "}\n/**/");
+  }
+
+  @Override
+  protected InspectionProfileEntry getInspection() {
+    return new ProblematicWhitespaceInspection();
+  }
+}