diff --git a/app/src/processing/app/contrib/AvailableContribution.java b/app/src/processing/app/contrib/AvailableContribution.java
index b30723682..046c49678 100644
--- a/app/src/processing/app/contrib/AvailableContribution.java
+++ b/app/src/processing/app/contrib/AvailableContribution.java
@@ -41,7 +41,8 @@ class AvailableContribution extends Contribution {
     this.type = type;
     this.link = params.get("download");
     
-    category = ContributionListing.getCategory(params.get("category"));
+    //category = ContributionListing.getCategory(params.get("category"));
+    categories = parseCategories(params.get("category"));
     name = params.get("name");
     authorList = params.get("authorList");
     url = params.get("url");
@@ -65,12 +66,11 @@ class AvailableContribution extends Contribution {
     // Unzip the file into the modes, tools, or libraries folder inside the 
     // sketchbook. Unzipping to /tmp is problematic because it may be on 
     // another file system, so move/rename operations will break.
-    File sketchbookContribFolder = type.getSketchbookFolder();
+//    File sketchbookContribFolder = type.getSketchbookFolder();
     File tempFolder = null; 
     
     try {
-      tempFolder = 
-        Base.createTempFolder(type.toString(), "tmp", sketchbookContribFolder);
+      tempFolder = type.createTempFolder();
     } catch (IOException e) {
       status.setErrorMessage("Could not create a temporary folder to install.");
       return null;
@@ -183,7 +183,7 @@ class AvailableContribution extends Contribution {
         PrintWriter writer = PApplet.createWriter(propFile);
 
         writer.println("name=" + getName());
-        writer.println("category=" + getCategory());
+        writer.println("category=" + getCategoryStr());
         writer.println("authorList=" + getAuthorList());
         writer.println("url=" + getUrl());
         writer.println("sentence=" + getSentence());
diff --git a/app/src/processing/app/contrib/Contribution.java b/app/src/processing/app/contrib/Contribution.java
index 759b85537..e09098add 100644
--- a/app/src/processing/app/contrib/Contribution.java
+++ b/app/src/processing/app/contrib/Contribution.java
@@ -21,9 +21,21 @@
 */
 package processing.app.contrib;
 
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+import processing.core.PApplet;
+
 
 abstract public class Contribution {
-  protected String category;      // "Sound"
+  static final List validCategories = 
+    Arrays.asList("3D", "Animation", "Data", "Geometry", "GUI", "Hardware", 
+                  "I/O", "Math", "Simulation", "Sound", "Typography", 
+                  "Utilities", "Video & Vision", "Other");
+
+  //protected String category;      // "Sound"
+  protected List<String> categories;  // "Sound", "Typography"
   protected String name;          // "pdf" or "PDF Export"
   protected String authorList;    // Ben Fry
   protected String url;           // http://processing.org
@@ -34,8 +46,37 @@ abstract public class Contribution {
   
   
   // "Sound"
-  public String getCategory() {
-    return category;
+//  public String getCategory() {
+//    return category;
+//  }
+
+  
+  // "Sound", "Utilities"... see valid list in ContributionListing
+  protected List<String> getCategories() {
+    return categories;
+  }
+  
+  
+  protected String getCategoryStr() {
+    StringBuilder sb = new StringBuilder();
+    for (String category : categories) {
+      sb.append(category);
+      sb.append(',');
+    }
+    sb.deleteCharAt(sb.length()-1);  // delete last comma
+    return sb.toString();
+  }
+  
+  
+  protected boolean hasCategory(String category) {
+    if (category != null) {
+      for (String c : categories) {
+        if (category.equalsIgnoreCase(c)) {
+          return true;
+        }
+      }
+    }
+    return false;
   }
 
 
@@ -105,4 +146,26 @@ abstract public class Contribution {
   boolean isDeletionFlagged() {
     return false;
   }
+  
+  
+  /**
+   * @return the list of categories that this contribution is part of
+   *         (e.g. "Typography / Geometry"). "Unknown" if the category null.
+   */
+  static public List<String> parseCategories(String categoryStr) {
+    List<String> outgoing = new ArrayList<String>();
+    
+    if (categoryStr != null) {
+      String[] listing = PApplet.trim(PApplet.split(categoryStr, ','));
+      for (String category : listing) {
+        if (validCategories.contains(category)) {
+          outgoing.add(category);
+        }
+      }
+    }
+    if (outgoing.size() == 0) {
+      outgoing.add("Unknown");
+    }
+    return outgoing;
+  }
 }
diff --git a/app/src/processing/app/contrib/ContributionListing.java b/app/src/processing/app/contrib/ContributionListing.java
index f9e211a8c..149cb3fdc 100644
--- a/app/src/processing/app/contrib/ContributionListing.java
+++ b/app/src/processing/app/contrib/ContributionListing.java
@@ -31,8 +31,9 @@ import processing.core.PApplet;
 
 
 public class ContributionListing {
+  // Stable URL that will redirect to wherever we're hosting the file
   static final String LISTING_URL =
-    "http://processing.org/contrib_generate/contributions.txt";
+    "http://download.processing.org/contributions.txt";
 
   static ContributionListing singleInstance;
 
@@ -44,12 +45,6 @@ public class ContributionListing {
   boolean hasDownloadedLatestList;
   ReentrantLock downloadingListingLock;
 
-  static final String[] validCategories = {
-    "3D", "Animation", "Compilations", "Data", "Geometry", "GUI",
-    "Hardware", "I/O", "Math", "Simulation", "Sound", "Typography",
-    "Utilities", "Video & Vision"
-  };
-
 
   private ContributionListing() {
     listeners = new ArrayList<ContributionChangeListener>();
@@ -103,53 +98,57 @@ public class ContributionListing {
 
 
   protected void replaceContribution(Contribution oldLib, Contribution newLib) {
-    if (oldLib == null || newLib == null) {
-      return;
-    }
+    if (oldLib != null && newLib != null) {
+      for (String category : oldLib.getCategories()) {
+        if (librariesByCategory.containsKey(category)) {
+          List<Contribution> list = librariesByCategory.get(category);
 
-    if (librariesByCategory.containsKey(oldLib.getCategory())) {
-      List<Contribution> list = librariesByCategory.get(oldLib.getCategory());
-
-      for (int i = 0; i < list.size(); i++) {
-        if (list.get(i) == oldLib) {
-          list.set(i, newLib);
+          for (int i = 0; i < list.size(); i++) {
+            if (list.get(i) == oldLib) {
+              list.set(i, newLib);
+            }
+          }
         }
       }
-    }
 
-    for (int i = 0; i < allContributions.size(); i++) {
-      if (allContributions.get(i) == oldLib) {
-        allContributions.set(i, newLib);
+      for (int i = 0; i < allContributions.size(); i++) {
+        if (allContributions.get(i) == oldLib) {
+          allContributions.set(i, newLib);
+        }
       }
-    }
 
-    notifyChange(oldLib, newLib);
+      notifyChange(oldLib, newLib);
+    }
   }
 
 
   private void addContribution(Contribution contribution) {
-    if (librariesByCategory.containsKey(contribution.getCategory())) {
-      List<Contribution> list = librariesByCategory.get(contribution.getCategory());
-      list.add(contribution);
-      Collections.sort(list, nameComparator);
+    for (String category : contribution.getCategories()) {
+      if (librariesByCategory.containsKey(category)) {
+        List<Contribution> list = librariesByCategory.get(category);
+        list.add(contribution);
+        Collections.sort(list, nameComparator);
 
-    } else {
-      ArrayList<Contribution> list = new ArrayList<Contribution>();
-      list.add(contribution);
-      librariesByCategory.put(contribution.getCategory(), list);
+      } else {
+        ArrayList<Contribution> list = new ArrayList<Contribution>();
+        list.add(contribution);
+        librariesByCategory.put(category, list);
+      }
+      allContributions.add(contribution);
+      notifyAdd(contribution);
+      Collections.sort(allContributions, nameComparator);
     }
-    allContributions.add(contribution);
-    notifyAdd(contribution);
-    Collections.sort(allContributions, nameComparator);
   }
 
 
-  protected void removeContribution(Contribution info) {
-    if (librariesByCategory.containsKey(info.getCategory())) {
-      librariesByCategory.get(info.getCategory()).remove(info);
+  protected void removeContribution(Contribution contribution) {
+    for (String category : contribution.getCategories()) {
+      if (librariesByCategory.containsKey(category)) {
+        librariesByCategory.get(category).remove(contribution);
+      }
     }
-    allContributions.remove(info);
-    notifyRemove(info);
+    allContributions.remove(contribution);
+    notifyRemove(contribution);
   }
 
 
@@ -209,12 +208,14 @@ public class ContributionListing {
 
 
   protected List<Contribution> getFilteredLibraryList(String category, List<String> filters) {
-    ArrayList<Contribution> filteredList = new ArrayList<Contribution>(allContributions);
+    ArrayList<Contribution> filteredList = 
+      new ArrayList<Contribution>(allContributions);
 
     Iterator<Contribution> it = filteredList.iterator();
     while (it.hasNext()) {
       Contribution libInfo = it.next();
-      if (category != null && !category.equals(libInfo.getCategory())) {
+      //if (category != null && !category.equals(libInfo.getCategory())) {
+      if (category != null && !libInfo.hasCategory(category)) {
         it.remove();
       } else {
         for (String filter : filters) {
@@ -254,7 +255,7 @@ public class ContributionListing {
     return contrib.getAuthorList() != null && contrib.getAuthorList().toLowerCase().matches(filter)
         || contrib.getSentence() != null && contrib.getSentence().toLowerCase().matches(filter)
         || contrib.getParagraph() != null && contrib.getParagraph().toLowerCase().matches(filter)
-        || contrib.getCategory() != null && contrib.getCategory().toLowerCase().matches(filter)
+        || contrib.hasCategory(filter)
         || contrib.getName() != null && contrib.getName().toLowerCase().matches(filter);
   }
 
@@ -396,39 +397,39 @@ public class ContributionListing {
   }
 
 
-  /**
-   * @return a lowercase string with all non-alphabetic characters removed
-   */
-  static protected String normalize(String s) {
-    return s.toLowerCase().replaceAll("^\\p{Lower}", "");
-  }
+//  /**
+//   * @return a lowercase string with all non-alphabetic characters removed
+//   */
+//  static protected String normalize(String s) {
+//    return s.toLowerCase().replaceAll("^\\p{Lower}", "");
+//  }
 
-
-  /**
-   * @return the proper, valid name of this category to be displayed in the UI
-   *         (e.g. "Typography / Geometry"). "Unknown" if the category null.
-   */
-  static public String getCategory(String category) {
-    if (category == null) {
-      return "Unknown";
-    }
-    String normCatName = normalize(category);
-
-    for (String validCatName : validCategories) {
-      String normValidCatName = normalize(validCatName);
-      if (normValidCatName.equals(normCatName)) {
-        return validCatName;
-      }
-    }
-    return category;
-  }
+  
+//  /**
+//   * @return the proper, valid name of this category to be displayed in the UI
+//   *         (e.g. "Typography / Geometry"). "Unknown" if the category null.
+//   */
+//  static public String getCategory(String category) {
+//    if (category == null) {
+//      return "Unknown";
+//    }
+//    String normCatName = normalize(category);
+//
+//    for (String validCatName : validCategories) {
+//      String normValidCatName = normalize(validCatName);
+//      if (normValidCatName.equals(normCatName)) {
+//        return validCatName;
+//      }
+//    }
+//    return category;
+//  }
 
 
   ArrayList<AvailableContribution> parseContribList(File file) {
     ArrayList<AvailableContribution> outgoing = new ArrayList<AvailableContribution>();
 
     if (file != null && file.exists()) {
-      String lines[] = PApplet.loadStrings(file);
+      String[] lines = PApplet.loadStrings(file);
 
       int start = 0;
       while (start < lines.length) {
diff --git a/app/src/processing/app/contrib/ContributionType.java b/app/src/processing/app/contrib/ContributionType.java
index 4c3b69fee..a2a943665 100644
--- a/app/src/processing/app/contrib/ContributionType.java
+++ b/app/src/processing/app/contrib/ContributionType.java
@@ -23,6 +23,7 @@ package processing.app.contrib;
 
 import java.io.File;
 import java.io.FileFilter;
+import java.io.IOException;
 import java.util.ArrayList;
 
 import processing.app.Base;
@@ -30,7 +31,6 @@ import processing.app.Editor;
 import processing.app.Library;
 
 public enum ContributionType {
-//    LIBRARY, LIBRARY_COMPILATION, TOOL, MODE;
   LIBRARY, TOOL, MODE;
 
     
@@ -38,8 +38,6 @@ public enum ContributionType {
     switch (this) {
     case LIBRARY:
       return "library";
-//      case LIBRARY_COMPILATION:
-//        return "compilation";
     case TOOL:
       return "tool";
     case MODE:
@@ -49,7 +47,10 @@ public enum ContributionType {
   };
   
   
-  /** Return Mode for mode, Tool for tool, etc. */
+  /** 
+   * Get this type name as a purtied up, capitalized version. 
+   * @return Mode for mode, Tool for tool, etc. 
+   */
   public String getTitle() {
     String s = toString();
     return Character.toUpperCase(s.charAt(0)) + s.substring(1);
@@ -60,8 +61,6 @@ public enum ContributionType {
     switch (this) {
     case LIBRARY:
       return "libraries";
-//      case LIBRARY_COMPILATION:
-//        return "libraries";
     case TOOL:
       return "tools";
     case MODE:
@@ -69,6 +68,26 @@ public enum ContributionType {
     }
     return null;  // should be unreachable
   }
+  
+  
+  public File createTempFolder() throws IOException {
+    return Base.createTempFolder(toString(), "tmp", getSketchbookFolder());
+  }
+  
+  
+  public boolean isTempFolderName(String name) {
+    return name.startsWith(toString()) && name.endsWith("tmp");
+  }
+  
+  
+//  public String getTempPrefix() {
+//    return toString();
+//  }
+//  
+//  
+//  public String getTempSuffix() {
+//    return "tmp";
+//  }
     
     
 //    public String getPropertiesName() {
@@ -78,16 +97,13 @@ public enum ContributionType {
     
   static public ContributionType fromName(String s) {
     if (s != null) {
-      if ("library".equals(s.toLowerCase())) {
+      if ("library".equalsIgnoreCase(s)) {
         return LIBRARY;
       }
-//        if ("compilation".equals(s.toLowerCase())) {
-//          return LIBRARY_COMPILATION;
-//        }
-      if ("tool".equals(s.toLowerCase())) {
+      if ("tool".equalsIgnoreCase(s)) {
         return TOOL;
       }
-      if ("mode".equals(s.toLowerCase())) {
+      if ("mode".equalsIgnoreCase(s)) {
         return MODE;
       }
     }
@@ -109,7 +125,9 @@ public enum ContributionType {
 
 
   boolean isCandidate(File potential) {
-    return (potential.isDirectory() && new File(potential, toString()).exists());
+    return (potential.isDirectory() && 
+            new File(potential, toString()).exists() && 
+            !isTempFolderName(potential.getName()));
   }
 
 
@@ -148,7 +166,8 @@ public enum ContributionType {
   LocalContribution load(Base base, File folder) {
     switch (this) {
     case LIBRARY:
-      return new Library(folder);
+      //return new Library(folder);
+      return Library.load(folder);
     case TOOL:
       return ToolContribution.load(folder);
     case MODE:
diff --git a/app/src/processing/app/contrib/LocalContribution.java b/app/src/processing/app/contrib/LocalContribution.java
index 7bf2878aa..20595a7ba 100644
--- a/app/src/processing/app/contrib/LocalContribution.java
+++ b/app/src/processing/app/contrib/LocalContribution.java
@@ -57,7 +57,7 @@ public abstract class LocalContribution extends Contribution {
 
       name = properties.get("name");
       id = properties.get("id");
-      category = ContributionListing.getCategory(properties.get("category"));
+      categories = parseCategories(properties.get("category"));
       if (name == null) {
         name = folder.getName();
       }
@@ -71,7 +71,6 @@ public abstract class LocalContribution extends Contribution {
       } catch (NumberFormatException e) {
         System.err.println("The version number for the “" + name + "” library is not set properly.");
         System.err.println("Please contact the library author to fix it according to the guidelines.");
-        //e.printStackTrace();
       }
       prettyVersion = properties.get("prettyVersion");
       
@@ -185,8 +184,8 @@ public abstract class LocalContribution extends Contribution {
   
   
   LocalContribution copyAndLoad(Editor editor, 
-                                    boolean confirmReplace, 
-                                    StatusPanel status) {
+                                boolean confirmReplace, 
+                                StatusPanel status) {
     ArrayList<LocalContribution> oldContribs = 
       getType().listContributions(editor);
     
@@ -283,7 +282,7 @@ public abstract class LocalContribution extends Contribution {
     if (backupFolder != null) {
       String libFolderName = getFolder().getName();
       String prefix = new SimpleDateFormat("yyyy-MM-dd").format(new Date());
-      final String backupName = prefix + "_" + libFolderName;
+      final String backupName = prefix + " " + libFolderName;
       File backupSubFolder = ContributionManager.getUniqueName(backupFolder, backupName);
 
       if (deleteOriginal) {
@@ -505,7 +504,7 @@ public abstract class LocalContribution extends Contribution {
   }
 
 
-  class IgnorableException extends Exception {
+  static protected class IgnorableException extends Exception {
     public IgnorableException(String msg) {
       super(msg);
     }
diff --git a/app/src/processing/app/contrib/ModeContribution.java b/app/src/processing/app/contrib/ModeContribution.java
index 44290d006..a55e2f1d8 100644
--- a/app/src/processing/app/contrib/ModeContribution.java
+++ b/app/src/processing/app/contrib/ModeContribution.java
@@ -94,13 +94,13 @@ public class ModeContribution extends LocalContribution {
     File[] potential = ContributionType.MODE.listCandidates(modesFolder);
     for (File folder : potential) {
       if (!existing.containsKey(folder)) {
-          try {
-            contribModes.add(new ModeContribution(base, folder, null));
-          } catch (IgnorableException ig) {
-            Base.log(ig.getMessage());
-          } catch (Exception e) {
-            e.printStackTrace();
-          }
+        try {
+          contribModes.add(new ModeContribution(base, folder, null));
+        } catch (IgnorableException ig) {
+          Base.log(ig.getMessage());
+        } catch (Exception e) {
+          e.printStackTrace();
+        }
       }
     }
   }