changed the way equal<%> and snip% interact. Specifically:

- snip% now implements equal<%>
   its equal-to? delegates to other-equal-to?.

 - snip%'s other-equal-to and equal-hash-code and
   equal-secondary-hash-code all just amount to using eq?. The
   setup is here just to make snip% be the one that declares
   that it implements equal<%> so that various snips can adjust
   other-equal-to? (and the hash code methods)

 - image-snip% no longer implements equal<%>
   (but it extends snip% and it overrides other-equal-to?
    and the hash-code methods to do what they always did)

original commit: 2f009ca529fcbe4ebe496379a5403cbcf1a0cd14

collects/scribblings/gui/image-snip-class.scrbl

@@ -1,7 +1,7 @@
 #lang scribble/doc
 @(require "common.ss")
 
-@defclass/title[image-snip% snip% (equal<%>)]{
+@defclass/title[image-snip% snip% ()]{
 
 An @scheme[image-snip%] is a snip that can display bitmap images
  (usually loaded from a file). When the image file cannot be found, a
@@ -43,19 +43,6 @@ secondary hash code for @this-obj[] (using the same notion of
 
 See also @scheme[equal<%>].}
 
-
-@defmethod[(equal-to? [snip (is-a?/c image-snip%)]
-                      [equal? (any/c any/c . -> . boolean?)])
-           boolean?]{
-
-Calls the @method[image-snip% other-equal-to?] method of @scheme[snip]
-(to simulate multi-method dispatch) in case @scheme[snip] provides a
-more specific equivalence comparison.
-
-See also @scheme[equal<%>].}
-
-
-
 @defmethod[(get-bitmap)
            (or/c (is-a?/c bitmap%) #f)]{
 
@@ -145,7 +132,7 @@ If @scheme[inline?] is not @scheme[#f], the image data will be saved
            boolean?]{
 
 Returns @scheme[#t] if @this-obj[] and @scheme[snip] both have bitmaps
-and the bitmaps are the same dimensions. If either has a mask bitmap
+and the bitmaps are the same. If either has a mask bitmap
 with the same dimensions as the main bitmap, then the masks must be
 the same (or if only one mask is present, it must correspond to a
 solid mask).

collects/scribblings/gui/snip-class.scrbl

@@ -1,7 +1,7 @@
 #lang scribble/doc
 @(require "common.ss")
 
-@defclass/title[snip% object% ()]{
+@defclass/title[snip% object% (equal<%>)]{
 
 A direct instance of @scheme[snip%] is uninteresting. Useful snips are
  defined by instantiating derived subclasses, but this class defines
@@ -217,7 +217,35 @@ Draws nothing.
 
 }}
 
+@defmethod[(equal-to? [snip (is-a?/c snip%)]
+                      [equal? (-> any/c any/c boolean?)])
+           boolean?]{
+@methspec{See @scheme[equal<%>].}
 
+@methimpl{Calls the @method[snip% other-equal-to?] method of @scheme[snip]
+(to simulate multi-method dispatch) in case @scheme[snip] provides a
+more specific equivalence comparison.}}
+
+@defmethod[(other-equal-to? [that (is-a?/c snip%)]
+                            [equal? (-> any/c any/ boolean?)])
+           boolean?]{
+@methimpl{Returns @racket[(eq? this that)].}
+}
+
+@defmethod[(equal-hash-code [hash-code (any/c . -> . exact-integer?)])
+           exact-integer?]{
+
+@methspec{See @scheme[equal<%>].}
+ 
+@methimpl{Returns @scheme[(eq-hash-code this)].}}
+
+@defmethod[(equal-secondary-hash-code [hash-code (any/c . -> . exact-integer?)])
+           exact-integer?]{
+
+@methspec{See @scheme[equal<%>].}
+ 
+@methimpl{Returns @scheme[1].}}
+                    
 @defmethod[(find-scroll-step [y real?])
            exact-nonnegative-integer?]{
 
@@ -234,7 +262,6 @@ Returns @scheme[0].
 
 }}
 
-
 @defmethod[(get-admin)
            (or/c (is-a?/c snip-admin%) false/c)]{