make duplicate registerItem() a no-op

projects/kiss-flixel/src/kiss_flixel/SimpleWindow.kiss

@@ -221,7 +221,6 @@
     (controls.clear)
     (inputTexts.clear)
     (keyHandler.clear)
-    (xHandler.clear)
     (makeXControls)
     (set nextControlX 0)
     (set nextControlY 0)

projects/kiss-tools/src/kiss_tools/KeyShortcutHandler.kiss

@@ -80,6 +80,10 @@
                         conflictMessage "Keyboard shortcut for $description conflicts with $existingKey"]
                     (if keys
                             (case existingKey
+                                // No harm in registering the same item twice:
+                                ((when (= otherItem item) (or (Final otherItem) (Cancel otherItem)))
+                                    (return))
+                                // Conflicting with a different one, on the other hand:
                                 ((or (Final _) (Cancel _))
                                     (tryCallOrThrow onBadShortcut conflictMessage false description existingKey))
                                 ((Prefix innerPrefixMap)