diff --git a/java/idea-ui/src/com/intellij/openapi/roots/ui/configuration/libraryEditor/DefaultLibraryRootsComponentDescriptor.java b/java/idea-ui/src/com/intellij/openapi/roots/ui/configuration/libraryEditor/DefaultLibraryRootsComponentDescriptor.java
index 0e01a37bf8a8..db5f76353b1c 100644
--- a/java/idea-ui/src/com/intellij/openapi/roots/ui/configuration/libraryEditor/DefaultLibraryRootsComponentDescriptor.java
+++ b/java/idea-ui/src/com/intellij/openapi/roots/ui/configuration/libraryEditor/DefaultLibraryRootsComponentDescriptor.java
@@ -20,7 +20,7 @@ import com.intellij.openapi.roots.AnnotationOrderRootType;
 import com.intellij.openapi.roots.JavadocOrderRootType;
 import com.intellij.openapi.roots.OrderRootType;
 import com.intellij.openapi.roots.libraries.ui.AttachRootButtonDescriptor;
-import com.intellij.openapi.roots.libraries.ui.AttachRootButtonDescriptorBase;
+import com.intellij.openapi.roots.libraries.ui.ChooserBasedAttachRootButtonDescriptor;
 import com.intellij.openapi.roots.libraries.ui.LibraryRootsComponentDescriptor;
 import com.intellij.openapi.roots.libraries.ui.OrderRootTypePresentation;
 import com.intellij.openapi.roots.ui.configuration.OrderRootTypeUIFactory;
@@ -46,8 +46,8 @@ public class DefaultLibraryRootsComponentDescriptor extends LibraryRootsComponen
   @NotNull
   @Override
   public List<? extends AttachRootButtonDescriptor> createAttachButtons() {
-    return Arrays.asList(new AttachClassesAction(), new AttachJarDirectoriesAction(), new AttachSourcesAction(),
-                         new AttachAnnotationsAction(), new AttachJavadocAction(), new AttachUrlJavadocAction());
+    return Arrays.asList(new AttachClassesDescriptor(), new AttachJarDirectoriesDescriptor(), new AttachSourcesDescriptor(),
+                         new AttachAnnotationsDescriptor(), new AttachJavadocDescriptor(), new AttachUrlJavadocDescriptor());
   }
 
   public static OrderRootTypePresentation getDefaultPresentation(OrderRootType type) {
@@ -55,8 +55,8 @@ public class DefaultLibraryRootsComponentDescriptor extends LibraryRootsComponen
     return new OrderRootTypePresentation(factory.getNodeText(), factory.getIcon());
   }
 
-  private static class AttachClassesAction extends AttachRootButtonDescriptorBase {
-    private AttachClassesAction() {
+  private static class AttachClassesDescriptor extends ChooserBasedAttachRootButtonDescriptor {
+    private AttachClassesDescriptor() {
       super(OrderRootType.CLASSES, ProjectBundle.message("module.libraries.attach.classes.button"));
     }
 
@@ -78,8 +78,8 @@ public class DefaultLibraryRootsComponentDescriptor extends LibraryRootsComponen
     }
   }
 
-  private static class AttachJarDirectoriesAction extends AttachRootButtonDescriptorBase {
-    private AttachJarDirectoriesAction() {
+  private static class AttachJarDirectoriesDescriptor extends ChooserBasedAttachRootButtonDescriptor {
+    private AttachJarDirectoriesDescriptor() {
       super(OrderRootType.CLASSES, ProjectBundle.message("module.libraries.attach.jar.directories.button"));
     }
 
@@ -105,8 +105,8 @@ public class DefaultLibraryRootsComponentDescriptor extends LibraryRootsComponen
     }
   }
 
-  private class AttachSourcesAction extends AttachRootButtonDescriptorBase {
-    private AttachSourcesAction() {
+  private class AttachSourcesDescriptor extends ChooserBasedAttachRootButtonDescriptor {
+    private AttachSourcesDescriptor() {
       super(OrderRootType.SOURCES, ProjectBundle.message("module.libraries.attach.sources.button"));
     }
 
@@ -124,8 +124,8 @@ public class DefaultLibraryRootsComponentDescriptor extends LibraryRootsComponen
     }
   }
 
-  private static class AttachAnnotationsAction extends AttachRootButtonDescriptorBase {
-    private AttachAnnotationsAction() {
+  private static class AttachAnnotationsDescriptor extends ChooserBasedAttachRootButtonDescriptor {
+    private AttachAnnotationsDescriptor() {
       super(AnnotationOrderRootType.getInstance(), ProjectBundle.message("attach.annotations.button"));
     }
 
@@ -143,8 +143,8 @@ public class DefaultLibraryRootsComponentDescriptor extends LibraryRootsComponen
     }
   }
 
-  private static class AttachJavadocAction extends AttachRootButtonDescriptorBase {
-    private AttachJavadocAction() {
+  private static class AttachJavadocDescriptor extends ChooserBasedAttachRootButtonDescriptor {
+    private AttachJavadocDescriptor() {
       super(JavadocOrderRootType.getInstance(), ProjectBundle.message("module.libraries.javadoc.attach.button"));
     }
 
@@ -157,8 +157,8 @@ public class DefaultLibraryRootsComponentDescriptor extends LibraryRootsComponen
     }
   }
 
-  private static class AttachUrlJavadocAction extends AttachRootButtonDescriptor {
-    private AttachUrlJavadocAction() {
+  private static class AttachUrlJavadocDescriptor extends AttachRootButtonDescriptor {
+    private AttachUrlJavadocDescriptor() {
       super(JavadocOrderRootType.getInstance(), ProjectBundle.message("module.libraries.javadoc.url.button"));
     }
 
diff --git a/platform/lang-impl/src/com/intellij/openapi/roots/libraries/LibraryType.java b/platform/lang-impl/src/com/intellij/openapi/roots/libraries/LibraryType.java
index fc1f2c0a4f07..f0b622d4329d 100644
--- a/platform/lang-impl/src/com/intellij/openapi/roots/libraries/LibraryType.java
+++ b/platform/lang-impl/src/com/intellij/openapi/roots/libraries/LibraryType.java
@@ -19,10 +19,19 @@ import com.intellij.openapi.extensions.ExtensionPointName;
 import com.intellij.openapi.roots.libraries.ui.LibraryEditorComponent;
 import com.intellij.openapi.roots.libraries.ui.LibraryPropertiesEditor;
 import com.intellij.openapi.roots.libraries.ui.LibraryRootsComponentDescriptor;
+import com.intellij.openapi.vfs.VirtualFile;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
+import java.util.List;
+
 /**
+ * Override this class to provide custom library type. The implementation should be registered in plugin.xml:
+ * <p>
+ * &lt;extensions defaultExtensionNs="com.intellij"&gt;<br>
+ * &nbsp;&nbsp;&lt;library.type implementation="qualified-class-name"/&gt;<br>
+ * &lt;/extensions&gt;
+ *
  * @author nik
  */
 public abstract class LibraryType<P extends LibraryProperties> extends LibraryPresentationProvider<P> {
@@ -32,12 +41,19 @@ public abstract class LibraryType<P extends LibraryProperties> extends LibraryPr
     super(libraryKind);
   }
 
+  /**
+   * @return text to show in 'New Library' popup
+   */
   @NotNull
   public abstract String getCreateActionName();
 
   @NotNull
   public abstract P createDefaultProperties();
 
+  /**
+   * Override this method to customize the library roots editor
+   * @return {@link com.intellij.openapi.roots.libraries.ui.LibraryRootsComponentDescriptor} instance
+   */
   @Nullable
   public LibraryRootsComponentDescriptor createLibraryRootsComponentDescriptor() {
     return null;
@@ -45,4 +61,9 @@ public abstract class LibraryType<P extends LibraryProperties> extends LibraryPr
 
   @Nullable
   public abstract LibraryPropertiesEditor createPropertiesEditor(@NotNull LibraryEditorComponent<P> properties);
+
+  @Override
+  public P detect(@NotNull List<VirtualFile> classesRoots) {
+    return null;
+  }
 }
diff --git a/platform/lang-impl/src/com/intellij/openapi/roots/libraries/ui/AttachRootButtonDescriptor.java b/platform/lang-impl/src/com/intellij/openapi/roots/libraries/ui/AttachRootButtonDescriptor.java
index 29cadc4f31da..755dd308e19e 100644
--- a/platform/lang-impl/src/com/intellij/openapi/roots/libraries/ui/AttachRootButtonDescriptor.java
+++ b/platform/lang-impl/src/com/intellij/openapi/roots/libraries/ui/AttachRootButtonDescriptor.java
@@ -21,6 +21,9 @@ import org.jetbrains.annotations.Nullable;
 import javax.swing.*;
 
 /**
+ * Describes an 'attach' button in the library roots component.
+ *
+ * @see ChooserBasedAttachRootButtonDescriptor
  * @author nik
  */
 public abstract class AttachRootButtonDescriptor {
diff --git a/platform/lang-impl/src/com/intellij/openapi/roots/libraries/ui/AttachRootButtonDescriptorBase.java b/platform/lang-impl/src/com/intellij/openapi/roots/libraries/ui/ChooserBasedAttachRootButtonDescriptor.java
similarity index 90%
rename from platform/lang-impl/src/com/intellij/openapi/roots/libraries/ui/AttachRootButtonDescriptorBase.java
rename to platform/lang-impl/src/com/intellij/openapi/roots/libraries/ui/ChooserBasedAttachRootButtonDescriptor.java
index c08e182cdb4d..1a33d06e4555 100644
--- a/platform/lang-impl/src/com/intellij/openapi/roots/libraries/ui/AttachRootButtonDescriptorBase.java
+++ b/platform/lang-impl/src/com/intellij/openapi/roots/libraries/ui/ChooserBasedAttachRootButtonDescriptor.java
@@ -26,8 +26,8 @@ import javax.swing.*;
 /**
 * @author nik
 */
-public abstract class AttachRootButtonDescriptorBase extends AttachRootButtonDescriptor {
-  public AttachRootButtonDescriptorBase(@NotNull OrderRootType rootType, @NotNull String buttonText) {
+public abstract class ChooserBasedAttachRootButtonDescriptor extends AttachRootButtonDescriptor {
+  public ChooserBasedAttachRootButtonDescriptor(@NotNull OrderRootType rootType, @NotNull String buttonText) {
     super(rootType, buttonText);
   }
 
diff --git a/platform/lang-impl/src/com/intellij/openapi/roots/libraries/ui/LibraryRootsComponentDescriptor.java b/platform/lang-impl/src/com/intellij/openapi/roots/libraries/ui/LibraryRootsComponentDescriptor.java
index cdd490d139de..4ae4fdf79a03 100644
--- a/platform/lang-impl/src/com/intellij/openapi/roots/libraries/ui/LibraryRootsComponentDescriptor.java
+++ b/platform/lang-impl/src/com/intellij/openapi/roots/libraries/ui/LibraryRootsComponentDescriptor.java
@@ -14,6 +14,7 @@ package com.intellij.openapi.roots.libraries.ui;
 
 import com.intellij.openapi.roots.OrderRootType;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
 
 import java.util.List;
 
@@ -21,8 +22,16 @@ import java.util.List;
  * @author nik
  */
 public abstract class LibraryRootsComponentDescriptor {
+  /**
+   * Defines presentation for root type nodes in the library roots editor
+   * @return custom presentation or {@code null} if default presentation should be used
+   */
+  @Nullable
   public abstract OrderRootTypePresentation getRootTypePresentation(@NotNull OrderRootType type);
 
+  /**
+   * @return descriptors for 'Attach' buttons in the library roots editor
+   */
   @NotNull
   public abstract List<? extends AttachRootButtonDescriptor> createAttachButtons();
 }