Remove uneeded methods, document reason why there is no else condition in doAction:

Source/GSStoryboardTransform.h

@@ -49,8 +49,6 @@ extern "C" {
 
 - (instancetype) initWithData: (NSData *)data;
 
-- (NSDictionary *) scenesMap;
-- (NSDictionary *) controllerMap;
 - (NSString *) initialViewControllerId;
 - (NSString *) applicationSceneId;
 

Source/GSStoryboardTransform.m

@@ -176,10 +176,12 @@
 - (IBAction) doAction: (id)sender
 {
   BOOL should = YES;
-  BOOL responds = [_sender respondsToSelector: @selector(shouldPerformSegueWithIdentifier:sender:)]  &&
-    ( [_sender isKindOfClass: [NSViewController class]] || [_sender isKindOfClass: [NSWindowController class]] );
 
-  if (responds)
+  // If the instance we are testing is a controller, then the value of should is set by this method....
+  // if it is not, as it is possible to initiate a segue from an NSMenuItem, then we don't, but should
+  // remains set to YES so that the logic to replace the destination controller is still called.
+  if ([_sender respondsToSelector: @selector(shouldPerformSegueWithIdentifier:sender:)]  &&
+      ([_sender isKindOfClass: [NSViewController class]] || [_sender isKindOfClass: [NSWindowController class]]))
     {
       should = [_sender shouldPerformSegueWithIdentifier: _identifier
                                                   sender: _sender];
@@ -343,16 +345,6 @@
   return _applicationSceneId;
 }
 
-- (NSDictionary *) scenesMap
-{
-  return _scenesMap;
-}
-
-- (NSDictionary *) controllerMap
-{
-  return _controllerMap;
-}
-
 - (NSMapTable *) segueMapForIdentifier: (NSString *)identifier
 {
   return [_identifierToSegueMap objectForKey: identifier];

Source/NSViewController.m

@@ -39,11 +39,6 @@
 #import "AppKit/NSStoryboard.h"
 #import "AppKit/NSWindowController.h"
 
-@interface NSStoryboardSegue (__ViewControllerPrivate__)
-- (void) _setDestinationController: (id)controller;
-- (void) _setSourceController: (id)controller;
-@end
-
 @implementation NSViewController
 
 - (id)initWithNibName:(NSString *)nibNameOrNil 

Source/NSWindowController.m

@@ -45,11 +45,6 @@
 
 #import "NSDocumentFrameworkPrivate.h"
 
-@interface NSStoryboardSegue (__WindowControllerPrivate__)
-- (void) _setDestinationController: (id)controller;
-- (void) _setSourceController: (id)controller;
-@end
-
 @implementation NSWindowController
 
 + (void) initialize
@@ -567,6 +562,8 @@
                             sender: (id)sender
 {
   NSStoryboardSegue *segue = [_segueMap objectForKey: identifier];
+  [self prepareForSegue: segue
+                 sender: sender];  
   [segue perform];
 }