Warning on leaving a page with unsaved content in textarea (#2910).

The warning can be turned off in the user's preference.

git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/trunk@4900 e93f8b46-1217-0410-a6f0-8f06a7374b81

app/models/user_preference.rb

@@ -51,4 +51,7 @@ class UserPreference < ActiveRecord::Base
   
   def comments_sorting; self[:comments_sorting] end
   def comments_sorting=(order); self[:comments_sorting]=order end
+  
+  def warn_on_leaving_unsaved; self[:warn_on_leaving_unsaved] || '1'; end
+  def warn_on_leaving_unsaved=(value); self[:warn_on_leaving_unsaved]=value; end
 end