diff -r c40b573c9f7a Lib/tkinter/__init__.py
--- a/Lib/tkinter/__init__.py	Sun Nov 03 14:34:25 2013 +0200
+++ b/Lib/tkinter/__init__.py	Sun Nov 03 14:57:01 2013 +0200
@@ -2857,10 +2857,16 @@
         relief, repeatdelay, repeatinterval, takefocus,
         troughcolor, width."""
         Widget.__init__(self, master, 'scrollbar', cnf, kw)
-    def activate(self, index):
-        """Display the element at INDEX with activebackground and activerelief.
-        INDEX can be "arrow1","slider" or "arrow2"."""
-        self.tk.call(self._w, 'activate', index)
+    def activate(self, element=None, *, index=None):
+        """If element is not None and is one of "arrow1", "slider" or "arrow2"
+        then it is marked as active. Otherwise the current active element is
+        returned, or None is returned in case no element is active."""
+        if index is not None:
+            warnings.warn("The 'index' keyword argument is deprecated and "
+                          "will be removed in 3.5. Use 'element' instead.",
+                          DeprecationWarning, 2)
+            element = index
+        return self.tk.call(self._w, 'activate', element) or None
     def delta(self, deltax, deltay):
         """Return the fractional change of the scrollbar setting if it
         would be moved by DELTAX or DELTAY pixels."""
@@ -2878,10 +2884,10 @@
         """Return the current fractional values (upper and lower end)
         of the slider position."""
         return self._getdoubles(self.tk.call(self._w, 'get'))
-    def set(self, *args):
+    def set(self, first, last):
         """Set the fractional values of the slider position (upper and
         lower ends as value between 0 and 1)."""
-        self.tk.call((self._w, 'set') + args)
+        self.tk.call(self._w, 'set', first, last)