added boolean functions for finding selectors

Gemfile.lock

@@ -1,7 +1,7 @@
 PATH
   remote: .
   specs:
-    compass (0.11.beta.3.a9b6d8c)
+    compass (0.11.beta.3.46eec53)
       chunky_png (~> 1.1.0)
       sass (>= 3.1.0.alpha.249)
 

lib/compass/sass_extensions/sprites/base.rb

@@ -71,6 +71,18 @@ module Compass
           @images.detect { |img| img.name == name}
         end
         
+        def has_hover?(name)
+          !image_for("#{name}_hover").nil?
+        end
+        
+        def has_target?(name)
+          !image_for("#{name}_target").nil?
+        end
+        
+        def has_active?(name)
+          !image_for("#{name}_active").nil?
+        end
+        
         def sprite_names
           image_names.map{|f| Compass::Sprites.sprite_name(f) }
         end