Redmine specify theme per project

theme.rb

module ApplicationHelper
  def current_theme
    # path to use diffrent theme for project and subprojects
    unless instance_variable_defined?(:@current_theme)
      theme = Setting.ui_theme
      if not @project.nil?
        if @project.root?
          if File.directory?("#{Rails.public_path}/themes/#{@project.identifier}")
            theme = @project.identifier
          end
        else
          if File.directory?("#{Rails.public_path}/themes/#{@project.ancestors.shift.identifier}")
            theme = @project.ancestors.shift.identifier
          end
        end
      end
      @current_theme = Redmine::Themes.theme(theme)
    end
    @current_theme

    # uncomment to use standard theme behavior
    #unless instance_variable_defined?(:@current_theme)
    #  @current_theme = Redmine::Themes.theme(Setting.ui_theme)
    #end
    #@current_theme
  end