Fix undo removing all filters in Firefox (#946) as well as the filters not being scrolled to the bottom when an item is added from the menu.

src/Filtering/Filter.coffee

@@ -271,7 +271,7 @@ Filter =
         select = $ 'select[name=filter]', section
         select.value = type
         Settings.selectFilter.call select
-        ta = $ 'textarea', section
-        tl = ta.textLength
-        ta.setSelectionRange tl, tl
-        ta.focus()
+        $.onExists section, 'textarea', (ta) ->
+          tl = ta.textLength
+          ta.setSelectionRange tl, tl
+          ta.focus()

src/General/Settings.coffee

@@ -441,10 +441,10 @@ Settings =
         name: name
         className: 'field'
         spellcheck: false
-      $.get name, Conf[name], (item) ->
-        (ta.value = item[name])
       $.on ta, 'change', $.cb.value
-      $.add div, ta
+      $.get name, Conf[name], (item) ->
+        ta.value = item[name]
+        $.add div, ta
       return
     $.extend div, <%= readHTML('Filter-guide.html') %>
     $('.warning', div).hidden = Conf['Filter']