Work around captcha bug causing captcha to go offscreen to the right. #550

src/Posting/Captcha.v2.coffee

@@ -34,6 +34,8 @@ Captcha.v2 =
     $.on window, 'captcha:success', =>
       # XXX Greasemonkey 1.x workaround to gain access to GM_* functions.
       $.queueTask => @save false
+    new MutationObserver(@watchBubbles.bind @).observe d.body,
+      childList: true
 
   initFrame: ->
     if token = $('.fbc-verification-token > textarea')?.value
@@ -228,3 +230,20 @@ Captcha.v2 =
           window.grecaptcha.reset(container.dataset.widgetID);
         })();
       '''
+
+  watchBubbles: (mutations) ->
+    for mutation in mutations
+      for node in mutation.addedNodes
+        if $ 'iframe[src^="https://www.google.com/recaptcha/api2/frame"]', node
+          new MutationObserver(@fixBubble.bind(@, node)).observe node,
+            attributes: true
+
+  fixBubble: (node) ->
+    {bottom, right, width} = node.getBoundingClientRect()
+    if (
+      bottom > 0 and          # not deliberately offscreen
+      right > doc.clientWidth # offscreen to right
+    )
+      qrLeft = QR.nodes.el.getBoundingClientRect().left
+      newLeft = Math.max 0, qrLeft - width
+      node.style.left = "#{newLeft}px"