Fall back to old edit mode for browsers that are not officially suppo…

…rted by Ace.

gollum.gemspec

@@ -32,6 +32,7 @@ Gem::Specification.new do |s|
   s.add_dependency('mustache', [">= 0.11.2", "< 1.0.0"])
   s.add_dependency('sanitize', "~> 2.0.0")
   s.add_dependency('nokogiri', "~> 1.4")
+  s.add_dependency('useragent', "~> 0.4.9")
 
   s.add_development_dependency('RedCloth')
   s.add_development_dependency('mocha')

lib/gollum/frontend/app.rb

@@ -2,6 +2,7 @@
 require 'sinatra'
 require 'gollum'
 require 'mustache/sinatra'
+require 'useragent'
 
 require 'gollum/frontend/views/layout'
 require 'gollum/frontend/views/editable'
@@ -25,6 +26,14 @@ class App < Sinatra::Base
 
     dir = File.dirname(File.expand_path(__FILE__))
 
+    # Detect unsupported browsers.
+    @@supported_browsers = ['Firefox', 'Chrome', 'Safari']
+
+    def is_supported( user_agent ) 
+      browser = UserAgent.parse( user_agent ).browser
+      @@supported_browsers.include? browser
+    end
+
     # We want to serve public assets for now
     set :public_folder, "#{dir}/public/gollum"
     set :static,         true
@@ -67,7 +76,7 @@ class App < Sinatra::Base
       @name = params[:splat].first
       wiki = Gollum::Wiki.new(settings.gollum_path, settings.wiki_options)
       if page = wiki.page(@name)
-        if page.format.to_s.include?('markdown')
+        if page.format.to_s.include?('markdown') && is_supported( request.user_agent )
           redirect '/livepreview/index.html?page=' + encodeURIComponent(@name)
         else
           @page = page