Fix bug causing captcha to sometimes not work when replying from index.

src/Posting/Captcha.t.coffee

@@ -12,14 +12,21 @@ Captcha.t =
   moreNeeded: ->
     return
 
+  getThread: ->
+    boardID = g.BOARD.ID
+    if QR.posts[0].thread is 'new'
+      threadID = '0'
+    else
+      threadID = '' + QR.posts[0].thread
+    {boardID, threadID}
+
   setup: (focus) ->
     return unless @isEnabled
 
     if !@nodes.container
       @nodes.container = $.el 'div', className: 'captcha-container'
       $.prepend @nodes.root, @nodes.container
-      boardID = g.BOARD.ID
-      threadID = '' + QR.posts[0].thread
+      Captcha.t.currentThread = Captcha.t.getThread()
       $.global ->
         el = document.querySelector '#qr .captcha-container'
         window.TCaptcha.init el, @boardID, +@threadID
@@ -28,7 +35,7 @@ Captcha.t =
             type: 'warning',
             content: '' + err
           }})
-      , {boardID, threadID}
+      , Captcha.t.currentThread
 
     if focus
       $('#t-resp').focus()
@@ -40,6 +47,13 @@ Captcha.t =
     $.rm @nodes.container
     delete @nodes.container
 
+  updateThread: ->
+    {boardID, threadID} = Captcha.t.currentThread
+    newThread = Captcha.t.getThread()
+    unless newThread.boardID is boardID and newThread.threadID is threadID
+      Captcha.t.destroy()
+      Captcha.t.setup()
+
   getOne: ->
     response = {}
     if @nodes.container

src/Posting/QR.post.coffee

@@ -74,6 +74,7 @@ QR.post = class
       (QR.posts[index-1] or QR.posts[index+1]).select()
     QR.posts.splice index, 1
     QR.status()
+    QR.captcha.updateThread?()
 
   delete: ->
     $.rm @nodes.el
@@ -129,6 +130,7 @@ QR.post = class
       when 'thread'
         (if @thread isnt 'new' then $.addClass else $.rmClass) QR.nodes.el, 'reply-to-thread'
         QR.status()
+        QR.captcha.updateThread?()
       when 'com'
         @updateComment()
       when 'filename'
@@ -403,3 +405,4 @@ QR.post = class
     post = QR.posts.splice(oldIndex, 1)[0]
     QR.posts.splice newIndex, 0, post
     QR.status()
+    QR.captcha.updateThread?()