diff -r 6eab274d3e34 Lib/idlelib/ZoomInOut.py
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Lib/idlelib/ZoomInOut.py	Mon May 13 16:32:15 2013 +0200
@@ -0,0 +1,76 @@
+# ZoomInOut extension
+# Press <Control-plus> to zoom in and <Control-minus> to zoom out
+
+
+def cursor(func):
+    """Decorator function for handling yview"""
+    def f(self, event):
+        if self._zero_pause:
+            self.pause_at_default()
+            return "break"
+        line, top, bot = self.store_cursor(event)
+        func(self)
+        self.restore_cursor(line, top, bot)
+    return f
+
+
+class ZoomInOut:
+
+    menudefs = [
+        ('windows', [
+            ('Zoom In', '<<zoom-in>>'),
+            ('Zoom Out', '<<zoom-out>>')
+        ])
+    ]
+
+    def __init__(self, editwin):
+        self.editwin = editwin
+        self.text = editwin.text
+        self._zero_pause = False
+
+    @cursor
+    def zoom_in_event(self):
+        self._zoom(offset=1)
+
+    @cursor
+    def zoom_out_event(self):
+        self._zoom(offset=-1)
+
+    def _zoom(self, offset):
+        fontname, fontsize, fontwidth = self.get_font()
+        new_fontsize = int(fontsize) + offset
+        if 7 < new_fontsize < 22:
+            self.text.configure(font=(fontname, new_fontsize, fontwidth))
+
+    def get_font(self):
+        font = self.text.configure('font')[-1]
+        if isinstance(font, str):
+            font = self.text.tk.split(font)
+        return font
+
+    def store_cursor(self, event):
+        x, y = event.x, event.y
+        coords = self.text.index('@%d,%d' % (x,y))
+        line = int(coords.split('.')[0])
+        top, bot = self.editwin.getwindowlines()
+        return line, top, bot
+
+    def restore_cursor(self, line, top, bot):
+        new_top, new_bot = self.editwin.getwindowlines()
+        new_h = max(new_bot-new_top-1, 1)
+
+        h = max(bot - top, 1)
+        ratio = (line - top) / (1.0 * h)
+        top2 = int(line - new_h * ratio)
+        self.text.yview('%i.%i' % (max(top2, 0), 0))
+
+    def control_release(self, event=None):
+        self._zero_pause = False
+
+    def pause_at_default(self, event=None):
+        self._zero_pause = True
+        if self._pause_id:
+            self.text.after_cancel(self._pause_id)
+        def unpause():
+            self._zero_pause = False
+        self._pause_id = self.text.after(250, unpause)
diff -r 6eab274d3e34 Lib/idlelib/config-extensions.def
--- a/Lib/idlelib/config-extensions.def	Sun May 12 23:08:28 2013 -0500
+++ b/Lib/idlelib/config-extensions.def	Mon May 13 16:32:15 2013 +0200
@@ -44,6 +44,12 @@
 [ZoomHeight_cfgBindings]
 zoom-height=<Alt-Key-2>
 
+[ZoomInOut]
+enable=1
+[ZoomInOut_cfgBindings]
+zoom-in=<Control-plus>
+zoom-out=<Control-minus>
+
 [ScriptBinding]
 enable=1
 enable_shell=0