Alt+click to pin threads in the catalog.

css/style.css

@@ -649,6 +649,7 @@ a.hide-announcement {
 .filter-highlight > .reply {
   box-shadow: -5px 0 rgba(255, 0, 0, .5);
 }
+.pinned .thumb,
 .filter-highlight .thumb {
   border: 2px solid rgba(255, 0, 0, .5);
 }

src/Filtering/Filter.coffee

@@ -110,7 +110,7 @@ Filter =
 
         # Highlight
         $.addClass @nodes.root, result.class
-        unless result.class in @highlights
+        unless @highlights and result.class in @highlights
           (@highlights or= []).push result.class
         if !@isReply and result.top
           @thread.isOnTop = true

src/General/Build.coffee

@@ -297,6 +297,7 @@ Build =
       className: 'catalog-thread'
       innerHTML: <%= importHTML('General/Thread-catalog-view') %>
 
+    $.addClass root, 'pinned' if thread.isPinned
     $.addClass root, thread.OP.highlights... if thread.OP.highlights
 
     if thread.isSticky

src/General/DataBoard.coffee

@@ -1,5 +1,5 @@
 class DataBoard
-  @keys = ['hiddenThreads', 'hiddenPosts', 'lastReadPosts', 'yourPosts', 'watchedThreads']
+  @keys = ['pinnedThreads', 'hiddenThreads', 'hiddenPosts', 'lastReadPosts', 'yourPosts', 'watchedThreads']
 
   constructor: (@key, sync, dontClean) ->
     @data = Conf[key]

src/General/Index.coffee

@@ -12,6 +12,11 @@ Index =
 
     return if g.VIEW isnt 'index' or g.BOARD.ID is 'f'
 
+    @db = new DataBoard 'pinnedThreads'
+    Thread.callbacks.push
+      name: 'Thread Pinning'
+      cb:   @node
+
     @button = $.el 'a',
       className: 'index-refresh-shortcut fa fa-refresh'
       title: 'Refresh Index'
@@ -112,6 +117,24 @@ Index =
       $.asap (-> $('.pagelist') or d.readyState isnt 'loading'), ->
         $.replace $('.pagelist'), Index.pagelist
 
+  node: ->
+    return unless data = Index.db.get {boardID: @board.ID, threadID: @ID}
+    @pin() if data.isPinned
+  togglePin: (thread) ->
+    if thread.isPinned
+      thread.unpin()
+      Index.db.delete
+        boardID:  thread.board.ID
+        threadID: thread.ID
+    else
+      thread.pin()
+      Index.db.set
+        boardID:  thread.board.ID
+        threadID: thread.ID
+        val: isPinned: thread.isPinned
+    Index.sort()
+    Index.buildIndex()
+
   cb:
     rootClass: ->
       (if Conf['Index Mode'] is 'catalog' then $.addClass else $.rmClass) Index.root, 'catalog-mode'

src/General/Thread.coffee

@@ -61,9 +61,17 @@ class Thread
       $.rm @catalogView
       ThreadHiding.hide @
       ThreadHiding.saveHiddenState @
+    else if e.altKey
+      Index.togglePin @
     else
       return
     e.preventDefault()
+  pin: ->
+    @isOnTop = @isPinned = true
+    $.addClass @catalogView, 'pinned' if @catalogView
+  unpin: ->
+    @isOnTop = @isPinned = false
+    $.rmClass  @catalogView, 'pinned' if @catalogView
 
   kill: ->
     @isDead = true