diff --git a/app/src/cc/arduino/contributions/libraries/ui/DropdownBuiltInLibrariesItem.java b/app/src/cc/arduino/contributions/libraries/ui/DropdownBuiltInLibrariesItem.java
deleted file mode 100644
index e807277c7..000000000
--- a/app/src/cc/arduino/contributions/libraries/ui/DropdownBuiltInLibrariesItem.java
+++ /dev/null
@@ -1,55 +0,0 @@
-/*
- * This file is part of Arduino.
- *
- * Copyright 2015 Arduino LLC (http://www.arduino.cc/)
- *
- * Arduino is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
- *
- * As a special exception, you may use this file as part of a free software
- * library without restriction.  Specifically, if other files instantiate
- * templates or use macros or inline functions from this file, or you compile
- * this file and link it with other files to produce an executable, this
- * file does not by itself cause the resulting executable to be covered by
- * the GNU General Public License.  This exception does not however
- * invalidate any other reasons why the executable file might be covered by
- * the GNU General Public License.
- */
-
-package cc.arduino.contributions.libraries.ui;
-
-import cc.arduino.contributions.filters.BuiltInPredicate;
-import cc.arduino.contributions.packages.DownloadableContribution;
-import cc.arduino.contributions.ui.DropdownItem;
-import com.google.common.base.Predicate;
-
-import static processing.app.I18n._;
-
-public class DropdownBuiltInLibrariesItem implements DropdownItem<DownloadableContribution> {
-
-  public String toString() {
-    return _("Built-in");
-  }
-
-  @Override
-  public Predicate<DownloadableContribution> getFilterPredicate() {
-    return new BuiltInPredicate();
-  }
-
-  @Override
-  public boolean equals(Object obj) {
-    return obj instanceof DropdownBuiltInLibrariesItem;
-  }
-
-}
diff --git a/app/src/cc/arduino/contributions/libraries/ui/LibraryManagerUI.java b/app/src/cc/arduino/contributions/libraries/ui/LibraryManagerUI.java
index 13b2eb335..b14807236 100644
--- a/app/src/cc/arduino/contributions/libraries/ui/LibraryManagerUI.java
+++ b/app/src/cc/arduino/contributions/libraries/ui/LibraryManagerUI.java
@@ -30,8 +30,9 @@ package cc.arduino.contributions.libraries.ui;
 
 import cc.arduino.contributions.libraries.ContributedLibrary;
 import cc.arduino.contributions.libraries.LibrariesIndexer;
+import cc.arduino.contributions.libraries.LibraryInstaller;
 import cc.arduino.contributions.packages.DownloadableContribution;
-import cc.arduino.contributions.packages.ui.InstallerJDialogUncaughtExceptionHandler;
+import cc.arduino.contributions.ui.InstallerJDialogUncaughtExceptionHandler;
 import cc.arduino.contributions.ui.*;
 import cc.arduino.utils.Progress;
 import com.google.common.base.Predicate;
diff --git a/app/src/cc/arduino/contributions/packages/ui/ContributionManagerUI.java b/app/src/cc/arduino/contributions/packages/ui/ContributionManagerUI.java
index 3c6a2ec9e..bf4980168 100644
--- a/app/src/cc/arduino/contributions/packages/ui/ContributionManagerUI.java
+++ b/app/src/cc/arduino/contributions/packages/ui/ContributionManagerUI.java
@@ -28,6 +28,7 @@
  */
 package cc.arduino.contributions.packages.ui;
 
+import cc.arduino.contributions.ui.InstallerJDialogUncaughtExceptionHandler;
 import cc.arduino.contributions.packages.ContributedPlatform;
 import cc.arduino.contributions.packages.ContributionInstaller;
 import cc.arduino.contributions.packages.ContributionsIndexer;
diff --git a/app/src/cc/arduino/contributions/packages/ui/InstallerJDialogUncaughtExceptionHandler.java b/app/src/cc/arduino/contributions/ui/InstallerJDialogUncaughtExceptionHandler.java
similarity index 98%
rename from app/src/cc/arduino/contributions/packages/ui/InstallerJDialogUncaughtExceptionHandler.java
rename to app/src/cc/arduino/contributions/ui/InstallerJDialogUncaughtExceptionHandler.java
index 80694f127..2c8e43dd0 100644
--- a/app/src/cc/arduino/contributions/packages/ui/InstallerJDialogUncaughtExceptionHandler.java
+++ b/app/src/cc/arduino/contributions/ui/InstallerJDialogUncaughtExceptionHandler.java
@@ -27,7 +27,7 @@
  * the GNU General Public License.
  */
 
-package cc.arduino.contributions.packages.ui;
+package cc.arduino.contributions.ui;
 
 import cc.arduino.contributions.ui.InstallerJDialog;
 
diff --git a/app/src/processing/app/Base.java b/app/src/processing/app/Base.java
index 1fcb91533..1b99420eb 100644
--- a/app/src/processing/app/Base.java
+++ b/app/src/processing/app/Base.java
@@ -25,7 +25,7 @@ package processing.app;
 import cc.arduino.contributions.VersionHelper;
 import cc.arduino.contributions.libraries.ContributedLibrary;
 import cc.arduino.contributions.libraries.LibrariesIndexer;
-import cc.arduino.contributions.libraries.ui.LibraryInstaller;
+import cc.arduino.contributions.libraries.LibraryInstaller;
 import cc.arduino.contributions.libraries.ui.LibraryManagerUI;
 import cc.arduino.contributions.packages.ContributedPlatform;
 import cc.arduino.contributions.packages.ContributionInstaller;
diff --git a/app/src/cc/arduino/contributions/libraries/ui/LibraryInstaller.java b/arduino-core/src/cc/arduino/contributions/libraries/LibraryInstaller.java
similarity index 97%
rename from app/src/cc/arduino/contributions/libraries/ui/LibraryInstaller.java
rename to arduino-core/src/cc/arduino/contributions/libraries/LibraryInstaller.java
index b7eca8aa5..a90f2f065 100644
--- a/app/src/cc/arduino/contributions/libraries/ui/LibraryInstaller.java
+++ b/arduino-core/src/cc/arduino/contributions/libraries/LibraryInstaller.java
@@ -26,10 +26,8 @@
  * invalidate any other reasons why the executable file might be covered by
  * the GNU General Public License.
  */
-package cc.arduino.contributions.libraries.ui;
+package cc.arduino.contributions.libraries;
 
-import cc.arduino.contributions.libraries.ContributedLibrary;
-import cc.arduino.contributions.libraries.LibrariesIndexer;
 import cc.arduino.contributions.packages.DownloadableContributionsDownloader;
 import cc.arduino.utils.ArchiveExtractor;
 import cc.arduino.utils.MultiStepProgress;