diff --git a/app/models/environment.rb b/app/models/environment.rb
index 39b2d0d..4cf1199 100644
--- a/app/models/environment.rb
+++ b/app/models/environment.rb
@@ -23,6 +23,7 @@ class Environment < ActiveRecord::Base
   has_many :profiles
 
   has_many :categories
+  has_many :display_categories, :class_name => 'Category', :conditions => 'display_color is not null ', :order => 'display_color'
 
   # #################################################
   # Attributes
diff --git a/test/unit/environment_test.rb b/test/unit/environment_test.rb
index f5cdd4f..42cc631 100644
--- a/test/unit/environment_test.rb
+++ b/test/unit/environment_test.rb
@@ -123,4 +123,17 @@ class EnvironmentTest < Test::Unit::TestCase
     assert cats.include?(subcat)
   end
 
+  should 'list displayable categories' do
+    env = Environment.create!(:name => 'a test environment')
+    cat1 = env.categories.create(:name => 'category one', :display_color => 1)
+    assert ! cat1.new_record?
+
+    cat2 = env.categories.create(:name => 'category two')
+    assert !cat2.new_record?
+
+    assert_equal 1,  env.display_categories.size
+    assert env.display_categories.include?(cat1)
+    assert !env.display_categories.include?(cat2)
+  end
+
 end
--
libgit2 0.21.2