diff --git a/doc/api/api_changes/2017-06-03-ES_unique_renderer.rst b/doc/api/api_changes/2017-06-03-ES_unique_renderer.rst
new file mode 100644
index 000000000000..3dd58e0a16f3
--- /dev/null
+++ b/doc/api/api_changes/2017-06-03-ES_unique_renderer.rst
@@ -0,0 +1,11 @@
+Unique identifier added to `RendererBase` classes
+`````````````````````````````````````````````````
+
+Since ``id()`` is not guaranteed to be unique between objects that exist at
+different times, a new private property ``_uid`` has been added to
+`RendererBase` which is used along with the renderer's ``id()`` to cache
+certain expensive operations.
+
+If a custom renderer does not subclass `RendererBase` or `MixedModeRenderer`,
+it is not required to implement this ``_uid`` property, but this may produce
+incorrect behavior when the renderers' ``id()`` clashes.
diff --git a/doc/api/api_changes/2017-06-11-DB_magnitude_spectrum.rst b/doc/api/api_changes/2017-06-11-DB_magnitude_spectrum.rst
new file mode 100644
index 000000000000..67efbb580a99
--- /dev/null
+++ b/doc/api/api_changes/2017-06-11-DB_magnitude_spectrum.rst
@@ -0,0 +1,31 @@
+Correct scaling of :func:`magnitude_spectrum()`
+```````````````````````````````````````````````
+
+The functions :func:`matplotlib.mlab.magnitude_spectrum()` and :func:`matplotlib.pyplot.magnitude_spectrum()` implicitly assumed the sum
+of windowing function values to be one. In Matplotlib and Numpy the
+standard windowing functions are scaled to have maximum value of one,
+which usually results in a sum of the order of n/2 for a n-point
+signal. Thus the amplitude scaling :func:`magnitude_spectrum()` was
+off by that amount when using standard windowing functions (`Bug 8417
+<https://github.com/matplotlib/matplotlib/issues/8417>`_ ). Now the
+behavior is consistent with :func:`matplotlib.pyplot.psd()` and
+:func:`scipy.signal.welch()`. The following example demonstrates the
+new and old scaling::
+
+    import matplotlib.pyplot as plt
+    import numpy as np
+    
+    tau, n = 10, 1024  # 10 second signal with 1024 points
+    T = tau/n  # sampling interval
+    t = np.arange(n)*T
+    
+    a = 4  # amplitude
+    x = a*np.sin(40*np.pi*t)  # 20 Hz sine with amplitude a
+    
+    # New correct behavior: Amplitude at 20 Hz is a/2
+    plt.magnitude_spectrum(x, Fs=1/T, sides='onesided', scale='linear')
+    
+    # Original behavior: Amplitude at 20 Hz is (a/2)*(n/2) for a Hanning window
+    w = np.hanning(n)  # default window is a Hanning window
+    plt.magnitude_spectrum(x*np.sum(w), Fs=1/T, sides='onesided', scale='linear')
+
diff --git a/lib/matplotlib/axes/_axes.py b/lib/matplotlib/axes/_axes.py
index 97a90c647664..90a1ef89ad7e 100644
--- a/lib/matplotlib/axes/_axes.py
+++ b/lib/matplotlib/axes/_axes.py
@@ -6666,8 +6666,7 @@ def magnitude_spectrum(self, x, Fs=None, Fc=None, window=None,
 
         scale : [ 'default' | 'linear' | 'dB' ]
             The scaling of the values in the *spec*.  'linear' is no scaling.
-            'dB' returns the values in dB scale.  When *mode* is 'density',
-            this is dB power (10 * log10).  Otherwise this is dB amplitude
+            'dB' returns the values in dB scale, i.e., the dB amplitude
             (20 * log10). 'default' is 'linear'.
 
         Fc : integer
diff --git a/lib/matplotlib/axes/_base.py b/lib/matplotlib/axes/_base.py
index 7948c14de8e9..4462cd620ce6 100644
--- a/lib/matplotlib/axes/_base.py
+++ b/lib/matplotlib/axes/_base.py
@@ -980,21 +980,8 @@ def cla(self):
             self.xaxis.minor = self._sharex.xaxis.minor
             x0, x1 = self._sharex.get_xlim()
             self.set_xlim(x0, x1, emit=False, auto=None)
-
-            # Save the current formatter/locator so we don't lose it
-            majf = self._sharex.xaxis.get_major_formatter()
-            minf = self._sharex.xaxis.get_minor_formatter()
-            majl = self._sharex.xaxis.get_major_locator()
-            minl = self._sharex.xaxis.get_minor_locator()
-
-            # This overwrites the current formatter/locator
-            self.xaxis._set_scale(self._sharex.xaxis.get_scale())
-
-            # Reset the formatter/locator
-            self.xaxis.set_major_formatter(majf)
-            self.xaxis.set_minor_formatter(minf)
-            self.xaxis.set_major_locator(majl)
-            self.xaxis.set_minor_locator(minl)
+            self.xaxis._scale = mscale.scale_factory(
+                    self._sharex.xaxis.get_scale(), self.xaxis)
         else:
             self.xaxis._set_scale('linear')
             try:
@@ -1007,21 +994,8 @@ def cla(self):
             self.yaxis.minor = self._sharey.yaxis.minor
             y0, y1 = self._sharey.get_ylim()
             self.set_ylim(y0, y1, emit=False, auto=None)
-
-            # Save the current formatter/locator so we don't lose it
-            majf = self._sharey.yaxis.get_major_formatter()
-            minf = self._sharey.yaxis.get_minor_formatter()
-            majl = self._sharey.yaxis.get_major_locator()
-            minl = self._sharey.yaxis.get_minor_locator()
-
-            # This overwrites the current formatter/locator
-            self.yaxis._set_scale(self._sharey.yaxis.get_scale())
-
-            # Reset the formatter/locator
-            self.yaxis.set_major_formatter(majf)
-            self.yaxis.set_minor_formatter(minf)
-            self.yaxis.set_major_locator(majl)
-            self.yaxis.set_minor_locator(minl)
+            self.yaxis._scale = mscale.scale_factory(
+                    self._sharey.yaxis.get_scale(), self.yaxis)
         else:
             self.yaxis._set_scale('linear')
             try:
diff --git a/lib/matplotlib/backend_bases.py b/lib/matplotlib/backend_bases.py
index 3cd6e34c73c1..72c0d7f2f6fb 100644
--- a/lib/matplotlib/backend_bases.py
+++ b/lib/matplotlib/backend_bases.py
@@ -41,6 +41,7 @@
 from contextlib import contextmanager
 import importlib
 import io
+import itertools
 import os
 import sys
 import time
@@ -100,6 +101,12 @@
 }
 
 
+# Used to ensure that caching based on renderer id() is unique without being as
+# expensive as a real UUID. 0 is used for renderers that don't derive from
+# here, so start at 1.
+_unique_renderer_id = itertools.count(1)
+
+
 def register_backend(format, backend, description=None):
     """
     Register a backend for saving to a given file format.
@@ -212,6 +219,10 @@ class RendererBase(object):
 
     """
     def __init__(self):
+        # A lightweight id for unique-ification purposes. Along with id(self),
+        # the combination should be unique enough to use as part of a cache key.
+        self._uid = next(_unique_renderer_id)
+
         self._texmanager = None
 
         self._text2path = textpath.TextToPath()
diff --git a/lib/matplotlib/backends/backend_agg.py b/lib/matplotlib/backends/backend_agg.py
index 223e088d71ba..35df7b6a3617 100644
--- a/lib/matplotlib/backends/backend_agg.py
+++ b/lib/matplotlib/backends/backend_agg.py
@@ -84,25 +84,18 @@ class RendererAgg(RendererBase):
 
     lock = threading.RLock()
     def __init__(self, width, height, dpi):
-        if __debug__: verbose.report('RendererAgg.__init__', 'debug-annoying')
         RendererBase.__init__(self)
 
         self.dpi = dpi
         self.width = width
         self.height = height
-        if __debug__: verbose.report('RendererAgg.__init__ width=%s, height=%s'%(width, height), 'debug-annoying')
         self._renderer = _RendererAgg(int(width), int(height), dpi, debug=False)
         self._filter_renderers = []
 
-        if __debug__: verbose.report('RendererAgg.__init__ _RendererAgg done',
-                                     'debug-annoying')
-
         self._update_methods()
         self.mathtext_parser = MathTextParser('Agg')
 
         self.bbox = Bbox.from_bounds(0, 0, self.width, self.height)
-        if __debug__: verbose.report('RendererAgg.__init__ done',
-                                     'debug-annoying')
 
     def __getstate__(self):
         # We only want to preserve the init keywords of the Renderer.
@@ -178,8 +171,6 @@ def draw_mathtext(self, gc, x, y, s, prop, angle):
         """
         Draw the math text using matplotlib.mathtext
         """
-        if __debug__: verbose.report('RendererAgg.draw_mathtext',
-                                     'debug-annoying')
         ox, oy, width, height, descent, font_image, used_characters = \
             self.mathtext_parser.parse(s, self.dpi, prop)
 
@@ -193,8 +184,6 @@ def draw_text(self, gc, x, y, s, prop, angle, ismath=False, mtext=None):
         """
         Render the text
         """
-        if __debug__: verbose.report('RendererAgg.draw_text', 'debug-annoying')
-
         if ismath:
             return self.draw_mathtext(gc, x, y, s, prop, angle)
 
@@ -279,9 +268,6 @@ def _get_agg_font(self, prop):
         """
         Get the font for text instance t, cacheing for efficiency
         """
-        if __debug__: verbose.report('RendererAgg._get_agg_font',
-                                     'debug-annoying')
-
         fname = findfont(prop)
         font = get_font(
             fname,
@@ -298,23 +284,15 @@ def points_to_pixels(self, points):
         convert point measures to pixes using dpi and the pixels per
         inch of the display
         """
-        if __debug__: verbose.report('RendererAgg.points_to_pixels',
-                                     'debug-annoying')
         return points*self.dpi/72.0
 
     def tostring_rgb(self):
-        if __debug__: verbose.report('RendererAgg.tostring_rgb',
-                                     'debug-annoying')
         return self._renderer.tostring_rgb()
 
     def tostring_argb(self):
-        if __debug__: verbose.report('RendererAgg.tostring_argb',
-                                     'debug-annoying')
         return self._renderer.tostring_argb()
 
     def buffer_rgba(self):
-        if __debug__: verbose.report('RendererAgg.buffer_rgba',
-                                     'debug-annoying')
         return self._renderer.buffer_rgba()
 
     def clear(self):
@@ -423,10 +401,6 @@ def new_figure_manager(num, *args, **kwargs):
     """
     Create a new figure manager instance
     """
-    if __debug__: verbose.report('backend_agg.new_figure_manager',
-                                 'debug-annoying')
-
-
     FigureClass = kwargs.pop('FigureClass', Figure)
     thisFig = FigureClass(*args, **kwargs)
     return new_figure_manager_given_figure(num, thisFig)
@@ -465,8 +439,6 @@ def draw(self):
         """
         Draw the figure using the renderer
         """
-        if __debug__: verbose.report('FigureCanvasAgg.draw', 'debug-annoying')
-
         self.renderer = self.get_renderer(cleared=True)
         # acquire a lock on the shared font cache
         RendererAgg.lock.acquire()
@@ -500,8 +472,6 @@ def tostring_rgb(self):
         -------
         bytes
         '''
-        if __debug__: verbose.report('FigureCanvasAgg.tostring_rgb',
-                                     'debug-annoying')
         return self.renderer.tostring_rgb()
 
     def tostring_argb(self):
@@ -515,8 +485,6 @@ def tostring_argb(self):
         bytes
 
         '''
-        if __debug__: verbose.report('FigureCanvasAgg.tostring_argb',
-                                     'debug-annoying')
         return self.renderer.tostring_argb()
 
     def buffer_rgba(self):
@@ -529,8 +497,6 @@ def buffer_rgba(self):
         -------
         bytes
         '''
-        if __debug__: verbose.report('FigureCanvasAgg.buffer_rgba',
-                                     'debug-annoying')
         return self.renderer.buffer_rgba()
 
     def print_raw(self, filename_or_obj, *args, **kwargs):
diff --git a/lib/matplotlib/backends/backend_cairo.py b/lib/matplotlib/backends/backend_cairo.py
index 7396452fa0e3..c41c74711214 100644
--- a/lib/matplotlib/backends/backend_cairo.py
+++ b/lib/matplotlib/backends/backend_cairo.py
@@ -27,8 +27,6 @@
 
 import numpy as np
 
-def _fn_name(): return sys._getframe(1).f_code.co_name
-
 try:
     import cairocffi as cairo
 except ImportError:
@@ -58,9 +56,6 @@ def _fn_name(): return sys._getframe(1).f_code.co_name
 from matplotlib.transforms   import Bbox, Affine2D
 from matplotlib.font_manager import ttfFontProperty
 
-_debug = False
-#_debug = True
-
 # Image::color_conv(format) for draw_image()
 if sys.byteorder == 'little':
     BYTE_FORMAT = 0 # BGRA
@@ -114,7 +109,6 @@ class RendererCairo(RendererBase):
     def __init__(self, dpi):
         """
         """
-        if _debug: print('%s.%s()' % (self.__class__.__name__, _fn_name()))
         self.dpi = dpi
         self.gc = GraphicsContextCairo (renderer=self)
         self.text_ctx = cairo.Context (
@@ -227,8 +221,6 @@ def draw_markers(self, gc, marker_path, marker_trans, path, transform, rgbFace=N
 
     def draw_image(self, gc, x, y, im):
         # bbox - not currently used
-        if _debug: print('%s.%s()' % (self.__class__.__name__, _fn_name()))
-
         if sys.byteorder == 'little':
             im = im[:, :, (2, 1, 0, 3)]
         else:
@@ -266,8 +258,6 @@ def draw_image(self, gc, x, y, im):
     def draw_text(self, gc, x, y, s, prop, angle, ismath=False, mtext=None):
         # Note: x,y are device/display coords, not user-coords, unlike other
         # draw_* methods
-        if _debug: print('%s.%s()' % (self.__class__.__name__, _fn_name()))
-
         if ismath:
             self._draw_mathtext(gc, x, y, s, prop, angle)
 
@@ -297,8 +287,6 @@ def draw_text(self, gc, x, y, s, prop, angle, ismath=False, mtext=None):
             ctx.restore()
 
     def _draw_mathtext(self, gc, x, y, s, prop, angle):
-        if _debug: print('%s.%s()' % (self.__class__.__name__, _fn_name()))
-
         ctx = gc.ctx
         width, height, descent, glyphs, rects = self.mathtext_parser.parse(
             s, self.dpi, prop)
@@ -335,19 +323,16 @@ def _draw_mathtext(self, gc, x, y, s, prop, angle):
 
 
     def flipy(self):
-        if _debug: print('%s.%s()' % (self.__class__.__name__, _fn_name()))
         return True
         #return False # tried - all draw objects ok except text (and images?)
         # which comes out mirrored!
 
 
     def get_canvas_width_height(self):
-        if _debug: print('%s.%s()' % (self.__class__.__name__, _fn_name()))
         return self.width, self.height
 
 
     def get_text_width_height_descent(self, s, prop, ismath):
-        if _debug: print('%s.%s()' % (self.__class__.__name__, _fn_name()))
         if ismath:
             width, height, descent, fonts, used_characters = self.mathtext_parser.parse(
                s, self.dpi, prop)
@@ -376,7 +361,6 @@ def get_text_width_height_descent(self, s, prop, ismath):
 
 
     def new_gc(self):
-        if _debug: print('%s.%s()' % (self.__class__.__name__, _fn_name()))
         self.gc.ctx.save()
         self.gc._alpha = 1.0
         self.gc._forced_alpha = False # if True, _alpha overrides A from RGBA
@@ -384,7 +368,6 @@ def new_gc(self):
 
 
     def points_to_pixels(self, points):
-        if _debug: print('%s.%s()' % (self.__class__.__name__, _fn_name()))
         return points/72.0 * self.dpi
 
 
@@ -488,7 +471,6 @@ def new_figure_manager(num, *args, **kwargs): # called by backends/__init__.py
     """
     Create a new figure manager instance
     """
-    if _debug: print('%s()' % (_fn_name()))
     FigureClass = kwargs.pop('FigureClass', Figure)
     thisFig = FigureClass(*args, **kwargs)
     return new_figure_manager_given_figure(num, thisFig)
diff --git a/lib/matplotlib/backends/backend_gdk.py b/lib/matplotlib/backends/backend_gdk.py
index 36583cf44402..8e9d424a8075 100644
--- a/lib/matplotlib/backends/backend_gdk.py
+++ b/lib/matplotlib/backends/backend_gdk.py
@@ -7,7 +7,6 @@
 import os
 import sys
 import warnings
-def fn_name(): return sys._getframe(1).f_code.co_name
 
 import gobject
 import gtk; gdk = gtk.gdk
@@ -24,8 +23,8 @@ def fn_name(): return sys._getframe(1).f_code.co_name
 import matplotlib
 from matplotlib import rcParams
 from matplotlib._pylab_helpers import Gcf
-from matplotlib.backend_bases import RendererBase, GraphicsContextBase, \
-     FigureManagerBase, FigureCanvasBase
+from matplotlib.backend_bases import (
+    RendererBase, GraphicsContextBase, FigureManagerBase, FigureCanvasBase)
 from matplotlib.cbook import restrict_dict, warn_deprecated
 from matplotlib.figure import Figure
 from matplotlib.mathtext import MathTextParser
@@ -33,7 +32,6 @@ def fn_name(): return sys._getframe(1).f_code.co_name
 from matplotlib.backends._backend_gdk import pixbuf_get_pixels_array
 
 backend_version = "%d.%d.%d" % gtk.pygtk_version
-_debug = False
 
 # Image formats that this backend supports - for FileChooser and print_figure()
 IMAGE_FORMAT = sorted(['bmp', 'eps', 'jpg', 'png', 'ps', 'svg']) # 'raw', 'rgb'
diff --git a/lib/matplotlib/backends/backend_gtk.py b/lib/matplotlib/backends/backend_gtk.py
index f9a2fa47edd0..a5dec05faeaa 100644
--- a/lib/matplotlib/backends/backend_gtk.py
+++ b/lib/matplotlib/backends/backend_gtk.py
@@ -4,7 +4,6 @@
 import six
 
 import os, sys, warnings
-def fn_name(): return sys._getframe(1).f_code.co_name
 
 if six.PY3:
     warnings.warn(
@@ -44,9 +43,6 @@ def fn_name(): return sys._getframe(1).f_code.co_name
 
 backend_version = "%d.%d.%d" % gtk.pygtk_version
 
-_debug = False
-#_debug = True
-
 # the true dots per inch on the screen; should be display dependent
 # see http://groups.google.com/groups?q=screen+dpi+x11&hl=en&lr=&ie=UTF-8&oe=UTF-8&safe=off&selm=7077.26e81ad5%40swift.cs.tcd.ie&rnum=5 for some info about screen dpi
 PIXELS_PER_INCH = 96
@@ -225,7 +221,6 @@ def __init__(self, figure):
                             "See Matplotlib usage FAQ for"
                             " more info on backends.",
                             alternative="GTKAgg")
-        if _debug: print('FigureCanvasGTK.%s' % fn_name())
         FigureCanvasBase.__init__(self, figure)
         gtk.DrawingArea.__init__(self)
 
@@ -261,7 +256,6 @@ def destroy(self):
             gobject.source_remove(self._idle_draw_id)
 
     def scroll_event(self, widget, event):
-        if _debug: print('FigureCanvasGTK.%s' % fn_name())
         x = event.x
         # flipy so y=0 is bottom of canvas
         y = self.allocation.height - event.y
@@ -273,7 +267,6 @@ def scroll_event(self, widget, event):
         return False  # finish event propagation?
 
     def button_press_event(self, widget, event):
-        if _debug: print('FigureCanvasGTK.%s' % fn_name())
         x = event.x
         # flipy so y=0 is bottom of canvas
         y = self.allocation.height - event.y
@@ -297,7 +290,6 @@ def button_press_event(self, widget, event):
         return False  # finish event propagation?
 
     def button_release_event(self, widget, event):
-        if _debug: print('FigureCanvasGTK.%s' % fn_name())
         x = event.x
         # flipy so y=0 is bottom of canvas
         y = self.allocation.height - event.y
@@ -305,21 +297,16 @@ def button_release_event(self, widget, event):
         return False  # finish event propagation?
 
     def key_press_event(self, widget, event):
-        if _debug: print('FigureCanvasGTK.%s' % fn_name())
         key = self._get_key(event)
-        if _debug: print("hit", key)
         FigureCanvasBase.key_press_event(self, key, guiEvent=event)
         return True  # stop event propagation
 
     def key_release_event(self, widget, event):
-        if _debug: print('FigureCanvasGTK.%s' % fn_name())
         key = self._get_key(event)
-        if _debug: print("release", key)
         FigureCanvasBase.key_release_event(self, key, guiEvent=event)
         return True  # stop event propagation
 
     def motion_notify_event(self, widget, event):
-        if _debug: print('FigureCanvasGTK.%s' % fn_name())
         if event.is_hint:
             x, y, state = event.window.get_pointer()
         else:
@@ -355,7 +342,6 @@ def _get_key(self, event):
         return key
 
     def configure_event(self, widget, event):
-        if _debug: print('FigureCanvasGTK.%s' % fn_name())
         if widget.window is None:
             return
         w, h = event.width, event.height
@@ -408,8 +394,6 @@ def _pixmap_prepare(self, width, height):
         Make sure _._pixmap is at least width, height,
         create new pixmap if necessary
         """
-        if _debug: print('FigureCanvasGTK.%s' % fn_name())
-
         create_pixmap = False
         if width > self._pixmap_width:
             # increase the pixmap in 10%+ (rather than 1 pixel) steps
@@ -438,8 +422,6 @@ def _render_figure(self, pixmap, width, height):
     def expose_event(self, widget, event):
         """Expose_event for all GTK backends. Should not be overridden.
         """
-        if _debug: print('FigureCanvasGTK.%s' % fn_name())
-
         if GTK_WIDGET_DRAWABLE(self):
             if self._need_redraw:
                 x, y, w, h = self.allocation
@@ -556,7 +538,6 @@ class FigureManagerGTK(FigureManagerBase):
 
     """
     def __init__(self, canvas, num):
-        if _debug: print('FigureManagerGTK.%s' % fn_name())
         FigureManagerBase.__init__(self, canvas, num)
 
         self.window = gtk.Window()
@@ -610,7 +591,6 @@ def notify_axes_change(fig):
         self.canvas.grab_focus()
 
     def destroy(self, *args):
-        if _debug: print('FigureManagerGTK.%s' % fn_name())
         if hasattr(self, 'toolbar') and self.toolbar is not None:
             self.toolbar.destroy()
         if hasattr(self, 'vbox'):
diff --git a/lib/matplotlib/backends/backend_gtk3.py b/lib/matplotlib/backends/backend_gtk3.py
index 6a1f74a30c65..c084f6d6dccc 100644
--- a/lib/matplotlib/backends/backend_gtk3.py
+++ b/lib/matplotlib/backends/backend_gtk3.py
@@ -4,7 +4,6 @@
 import six
 
 import os, sys
-def fn_name(): return sys._getframe(1).f_code.co_name
 
 try:
     import gi
@@ -28,23 +27,21 @@ def fn_name(): return sys._getframe(1).f_code.co_name
 
 import matplotlib
 from matplotlib._pylab_helpers import Gcf
-from matplotlib.backend_bases import RendererBase, GraphicsContextBase, \
-     FigureManagerBase, FigureCanvasBase, NavigationToolbar2, cursors, TimerBase
-from matplotlib.backend_bases import (ShowBase, ToolContainerBase,
-                                      StatusbarBase)
+from matplotlib.backend_bases import (
+    FigureCanvasBase, FigureManagerBase, GraphicsContextBase,
+    NavigationToolbar2, RendererBase, TimerBase, cursors)
+from matplotlib.backend_bases import (
+    ShowBase, ToolContainerBase, StatusbarBase)
 from matplotlib.backend_managers import ToolManager
-from matplotlib import backend_tools
-
 from matplotlib.cbook import is_writable_file_like
 from matplotlib.figure import Figure
 from matplotlib.widgets import SubplotTool
 
-from matplotlib import cbook, colors as mcolors, lines, verbose, rcParams
-
-backend_version = "%s.%s.%s" % (Gtk.get_major_version(), Gtk.get_micro_version(), Gtk.get_minor_version())
+from matplotlib import (
+    backend_tools, cbook, colors as mcolors, lines, verbose, rcParams)
 
-_debug = False
-#_debug = True
+backend_version = "%s.%s.%s" % (
+    Gtk.get_major_version(), Gtk.get_micro_version(), Gtk.get_minor_version())
 
 # the true dots per inch on the screen; should be display dependent
 # see http://groups.google.com/groups?q=screen+dpi+x11&hl=en&lr=&ie=UTF-8&oe=UTF-8&safe=off&selm=7077.26e81ad5%40swift.cs.tcd.ie&rnum=5 for some info about screen dpi
@@ -119,7 +116,7 @@ def _on_timer(self):
             self._timer = None
             return False
 
-class FigureCanvasGTK3 (Gtk.DrawingArea, FigureCanvasBase):
+class FigureCanvasGTK3(Gtk.DrawingArea, FigureCanvasBase):
     keyvald = {65507 : 'control',
                65505 : 'shift',
                65513 : 'alt',
@@ -185,7 +182,6 @@ class FigureCanvasGTK3 (Gtk.DrawingArea, FigureCanvasBase):
                   Gdk.EventMask.SCROLL_MASK)
 
     def __init__(self, figure):
-        if _debug: print('FigureCanvasGTK3.%s' % fn_name())
         FigureCanvasBase.__init__(self, figure)
         GObject.GObject.__init__(self)
 
@@ -219,7 +215,6 @@ def destroy(self):
             GLib.source_remove(self._idle_draw_id)
 
     def scroll_event(self, widget, event):
-        if _debug: print('FigureCanvasGTK3.%s' % fn_name())
         x = event.x
         # flipy so y=0 is bottom of canvas
         y = self.get_allocation().height - event.y
@@ -231,7 +226,6 @@ def scroll_event(self, widget, event):
         return False  # finish event propagation?
 
     def button_press_event(self, widget, event):
-        if _debug: print('FigureCanvasGTK3.%s' % fn_name())
         x = event.x
         # flipy so y=0 is bottom of canvas
         y = self.get_allocation().height - event.y
@@ -239,7 +233,6 @@ def button_press_event(self, widget, event):
         return False  # finish event propagation?
 
     def button_release_event(self, widget, event):
-        if _debug: print('FigureCanvasGTK3.%s' % fn_name())
         x = event.x
         # flipy so y=0 is bottom of canvas
         y = self.get_allocation().height - event.y
@@ -247,21 +240,16 @@ def button_release_event(self, widget, event):
         return False  # finish event propagation?
 
     def key_press_event(self, widget, event):
-        if _debug: print('FigureCanvasGTK3.%s' % fn_name())
         key = self._get_key(event)
-        if _debug: print("hit", key)
         FigureCanvasBase.key_press_event(self, key, guiEvent=event)
         return True  # stop event propagation
 
     def key_release_event(self, widget, event):
-        if _debug: print('FigureCanvasGTK3.%s' % fn_name())
         key = self._get_key(event)
-        if _debug: print("release", key)
         FigureCanvasBase.key_release_event(self, key, guiEvent=event)
         return True  # stop event propagation
 
     def motion_notify_event(self, widget, event):
-        if _debug: print('FigureCanvasGTK3.%s' % fn_name())
         if event.is_hint:
             t, x, y, state = event.window.get_pointer()
         else:
@@ -279,9 +267,6 @@ def enter_notify_event(self, widget, event):
         FigureCanvasBase.enter_notify_event(self, event)
 
     def size_allocate(self, widget, allocation):
-        if _debug:
-            print("FigureCanvasGTK3.%s" % fn_name())
-            print("size_allocate (%d x %d)" % (allocation.width, allocation.height))
         dpival = self.figure.dpi
         winch = allocation.width / dpival
         hinch = allocation.height / dpival
@@ -309,7 +294,6 @@ def _get_key(self, event):
         return key
 
     def configure_event(self, widget, event):
-        if _debug: print('FigureCanvasGTK3.%s' % fn_name())
         if widget.get_property("window") is None:
             return
         w, h = event.width, event.height
@@ -395,7 +379,6 @@ class FigureManagerGTK3(FigureManagerBase):
 
     """
     def __init__(self, canvas, num):
-        if _debug: print('FigureManagerGTK3.%s' % fn_name())
         FigureManagerBase.__init__(self, canvas, num)
 
         self.window = Gtk.Window()
@@ -468,16 +451,15 @@ def notify_axes_change(fig):
         self.canvas.grab_focus()
 
     def destroy(self, *args):
-        if _debug: print('FigureManagerGTK3.%s' % fn_name())
         self.vbox.destroy()
         self.window.destroy()
         self.canvas.destroy()
         if self.toolbar:
             self.toolbar.destroy()
 
-        if Gcf.get_num_fig_managers()==0 and \
-               not matplotlib.is_interactive() and \
-               Gtk.main_level() >= 1:
+        if (Gcf.get_num_fig_managers() == 0 and
+                not matplotlib.is_interactive() and
+                Gtk.main_level() >= 1):
             Gtk.main_quit()
 
     def show(self):
@@ -497,7 +479,7 @@ def _get_toolbar(self):
         # must be inited after the window, drawingArea and figure
         # attrs are set
         if rcParams['toolbar'] == 'toolbar2':
-            toolbar = NavigationToolbar2GTK3 (self.canvas, self.window)
+            toolbar = NavigationToolbar2GTK3(self.canvas, self.window)
         elif rcParams['toolbar'] == 'toolmanager':
             toolbar = ToolbarGTK3(self.toolmanager)
         else:
@@ -941,7 +923,8 @@ def trigger(self, sender, event, data=None):
     icon_filename = 'matplotlib.png'
 else:
     icon_filename = 'matplotlib.svg'
-window_icon = os.path.join(matplotlib.rcParams['datapath'], 'images', icon_filename)
+window_icon = os.path.join(
+    matplotlib.rcParams['datapath'], 'images', icon_filename)
 
 
 def error_msg_gtk(msg, parent=None):
@@ -951,7 +934,7 @@ def error_msg_gtk(msg, parent=None):
             parent = None
 
     if not isinstance(msg, six.string_types):
-        msg = ','.join(map(str,msg))
+        msg = ','.join(map(str, msg))
 
     dialog = Gtk.MessageDialog(
         parent         = parent,
diff --git a/lib/matplotlib/backends/backend_gtkcairo.py b/lib/matplotlib/backends/backend_gtkcairo.py
index 93bb69857a1f..1440b85044a9 100644
--- a/lib/matplotlib/backends/backend_gtkcairo.py
+++ b/lib/matplotlib/backends/backend_gtkcairo.py
@@ -8,25 +8,20 @@
 import six
 
 import gtk
-if gtk.pygtk_version < (2,7,0):
+if gtk.pygtk_version < (2, 7, 0):
     import cairo.gtk
 
 from matplotlib.backends import backend_cairo
 from matplotlib.backends.backend_gtk import *
 
-backend_version = 'PyGTK(%d.%d.%d) ' % gtk.pygtk_version + \
-                  'Pycairo(%s)' % backend_cairo.backend_version
-
-
-_debug = False
-#_debug = True
+backend_version = ('PyGTK(%d.%d.%d) ' % gtk.pygtk_version
+                   + 'Pycairo(%s)' % backend_cairo.backend_version)
 
 
 def new_figure_manager(num, *args, **kwargs):
     """
     Create a new figure manager instance
     """
-    if _debug: print('backend_gtkcairo.%s()' % fn_name())
     FigureClass = kwargs.pop('FigureClass', Figure)
     thisFig = FigureClass(*args, **kwargs)
     return new_figure_manager_given_figure(num, thisFig)
@@ -55,8 +50,7 @@ class FigureCanvasGTKCairo(backend_cairo.FigureCanvasCairo, FigureCanvasGTK):
 
     def _renderer_init(self):
         """Override to use cairo (rather than GDK) renderer"""
-        if _debug: print('%s.%s()' % (self.__class__.__name__, _fn_name()))
-        self._renderer = RendererGTKCairo (self.figure.dpi)
+        self._renderer = RendererGTKCairo(self.figure.dpi)
 
 
 class FigureManagerGTKCairo(FigureManagerGTK):
diff --git a/lib/matplotlib/backends/backend_mixed.py b/lib/matplotlib/backends/backend_mixed.py
index 40d7fd64398c..a93ef062f279 100644
--- a/lib/matplotlib/backends/backend_mixed.py
+++ b/lib/matplotlib/backends/backend_mixed.py
@@ -5,6 +5,7 @@
 
 import six
 
+import matplotlib.backend_bases
 from matplotlib.backends.backend_agg import RendererAgg
 from matplotlib.tight_bbox import process_figure_for_rasterizing
 
@@ -49,6 +50,9 @@ def __init__(self, figure, width, height, dpi, vector_renderer,
         if raster_renderer_class is None:
             raster_renderer_class = RendererAgg
 
+        # See matplotlib.backend_bases.RendererBase._uid.
+        self._uid = next(matplotlib.backend_bases._unique_renderer_id)
+
         self._raster_renderer_class = raster_renderer_class
         self._width = width
         self._height = height
diff --git a/lib/matplotlib/backends/backend_ps.py b/lib/matplotlib/backends/backend_ps.py
index ffad5187c9c2..0e4e2011841c 100644
--- a/lib/matplotlib/backends/backend_ps.py
+++ b/lib/matplotlib/backends/backend_ps.py
@@ -9,7 +9,6 @@
 from six.moves import StringIO
 
 import glob, os, shutil, sys, time, datetime
-def _fn_name(): return sys._getframe(1).f_code.co_name
 import io
 
 from tempfile import mkstemp
diff --git a/lib/matplotlib/backends/backend_qt4.py b/lib/matplotlib/backends/backend_qt4.py
index a10dd19a1788..c90a36c2a648 100644
--- a/lib/matplotlib/backends/backend_qt4.py
+++ b/lib/matplotlib/backends/backend_qt4.py
@@ -25,12 +25,11 @@
 
 from .qt_compat import QtCore, QtWidgets, _getSaveFileName, __version__
 
-from .backend_qt5 import (backend_version, SPECIAL_KEYS, SUPER, ALT, CTRL,
-                        SHIFT, MODIFIER_KEYS, fn_name, cursord,
-                        draw_if_interactive, _create_qApp, show, TimerQT,
-                        MainWindow, FigureManagerQT, NavigationToolbar2QT,
-                        SubplotToolQt, error_msg_qt, exception_handler)
-
+from .backend_qt5 import (
+    backend_version, SPECIAL_KEYS, SUPER, ALT, CTRL, SHIFT, MODIFIER_KEYS,
+    cursord, draw_if_interactive, _create_qApp, show, TimerQT, MainWindow,
+    FigureManagerQT, NavigationToolbar2QT, SubplotToolQt, error_msg_qt,
+    exception_handler)
 from .backend_qt5 import FigureCanvasQT as FigureCanvasQT5
 
 DEBUG = False
diff --git a/lib/matplotlib/backends/backend_qt5.py b/lib/matplotlib/backends/backend_qt5.py
index 9c3518ffc9e7..291c0caab68f 100644
--- a/lib/matplotlib/backends/backend_qt5.py
+++ b/lib/matplotlib/backends/backend_qt5.py
@@ -90,11 +90,6 @@
                         QtCore.Qt.Key_Meta)
 
 
-def fn_name():
-    return sys._getframe(1).f_code.co_name
-
-DEBUG = False
-
 cursord = {
     cursors.MOVE: QtCore.Qt.SizeAllCursor,
     cursors.HAND: QtCore.Qt.PointingHandCursor,
@@ -123,8 +118,6 @@ def _create_qApp():
     global qApp
 
     if qApp is None:
-        if DEBUG:
-            print("Starting up QApplication")
         app = QtWidgets.QApplication.instance()
         if app is None:
             # check for DISPLAY env variable on X11 build of Qt
@@ -233,8 +226,6 @@ class FigureCanvasQT(QtWidgets.QWidget, FigureCanvasBase):
                }
 
     def __init__(self, figure):
-        if DEBUG:
-            print('FigureCanvasQt qt5: ', figure)
         _create_qApp()
 
         # NB: Using super for this call to avoid a TypeError:
@@ -292,8 +283,6 @@ def mousePressEvent(self, event):
         if button is not None:
             FigureCanvasBase.button_press_event(self, x, y, button,
                                                 guiEvent=event)
-        if DEBUG:
-            print('button pressed:', event.button())
 
     def mouseDoubleClickEvent(self, event):
         x, y = self.mouseEventCoords(event.pos())
@@ -302,13 +291,10 @@ def mouseDoubleClickEvent(self, event):
             FigureCanvasBase.button_press_event(self, x, y,
                                                 button, dblclick=True,
                                                 guiEvent=event)
-        if DEBUG:
-            print('button doubleclicked:', event.button())
 
     def mouseMoveEvent(self, event):
         x, y = self.mouseEventCoords(event)
         FigureCanvasBase.motion_notify_event(self, x, y, guiEvent=event)
-        # if DEBUG: print('mouse move')
 
     def mouseReleaseEvent(self, event):
         x, y = self.mouseEventCoords(event)
@@ -316,8 +302,6 @@ def mouseReleaseEvent(self, event):
         if button is not None:
             FigureCanvasBase.button_release_event(self, x, y, button,
                                                   guiEvent=event)
-        if DEBUG:
-            print('button released')
 
     def wheelEvent(self, event):
         x, y = self.mouseEventCoords(event)
@@ -326,28 +310,18 @@ def wheelEvent(self, event):
             steps = event.angleDelta().y() / 120
         else:
             steps = event.pixelDelta().y()
-
-        if steps != 0:
+        if steps:
             FigureCanvasBase.scroll_event(self, x, y, steps, guiEvent=event)
-            if DEBUG:
-                print('scroll event: delta = %i, '
-                      'steps = %i ' % (event.delta(), steps))
 
     def keyPressEvent(self, event):
         key = self._get_key(event)
-        if key is None:
-            return
-        FigureCanvasBase.key_press_event(self, key, guiEvent=event)
-        if DEBUG:
-            print('key press', key)
+        if key is not None:
+            FigureCanvasBase.key_press_event(self, key, guiEvent=event)
 
     def keyReleaseEvent(self, event):
         key = self._get_key(event)
-        if key is None:
-            return
-        FigureCanvasBase.key_release_event(self, key, guiEvent=event)
-        if DEBUG:
-            print('key release', key)
+        if key is not None:
+            FigureCanvasBase.key_release_event(self, key, guiEvent=event)
 
     @property
     def keyAutoRepeat(self):
@@ -363,9 +337,6 @@ def keyAutoRepeat(self, val):
     def resizeEvent(self, event):
         w = event.size().width() * self._dpi_ratio
         h = event.size().height() * self._dpi_ratio
-        if DEBUG:
-            print('resize (%d x %d)' % (w, h))
-            print("FigureCanvasQt.resizeEvent(%d, %d)" % (w, h))
         dpival = self.figure.dpi
         winch = w / dpival
         hinch = h / dpival
@@ -478,8 +449,6 @@ class FigureManagerQT(FigureManagerBase):
     """
 
     def __init__(self, canvas, num):
-        if DEBUG:
-            print('FigureManagerQT.%s' % fn_name())
         FigureManagerBase.__init__(self, canvas, num)
         self.canvas = canvas
         self.window = MainWindow()
@@ -578,11 +547,8 @@ def destroy(self, *args):
             return
         self.window._destroying = True
         self.window.destroyed.connect(self._widgetclosed)
-
         if self.toolbar:
             self.toolbar.destroy()
-        if DEBUG:
-            print("destroy figure manager")
         self.window.close()
 
     def get_window_title(self):
@@ -712,8 +678,6 @@ def set_message(self, s):
             self.locLabel.setText(s)
 
     def set_cursor(self, cursor):
-        if DEBUG:
-            print('Set cursor', cursor)
         self.canvas.setCursor(cursord[cursor])
 
     def draw_rubberband(self, event, x0, y0, x1, y1):
@@ -724,7 +688,7 @@ def draw_rubberband(self, event, x0, y0, x1, y1):
         w = abs(x1 - x0)
         h = abs(y1 - y0)
 
-        rect = [int(val)for val in (min(x0, x1), min(y0, y1), w, h)]
+        rect = [int(val) for val in (min(x0, x1), min(y0, y1), w, h)]
         self.canvas.drawRectangle(rect)
 
     def remove_rubberband(self):
diff --git a/lib/matplotlib/backends/backend_tkagg.py b/lib/matplotlib/backends/backend_tkagg.py
index af0ed62f9d81..371126d3d660 100644
--- a/lib/matplotlib/backends/backend_tkagg.py
+++ b/lib/matplotlib/backends/backend_tkagg.py
@@ -719,7 +719,6 @@ def __init__(self, canvas, window):
         self.canvas = canvas
         self.window = window
         self._idle = True
-        #Tk.Frame.__init__(self, master=self.canvas._tkcanvas)
         NavigationToolbar2.__init__(self, canvas)
 
     def destroy(self, *args):
@@ -731,11 +730,10 @@ def set_message(self, s):
 
     def draw_rubberband(self, event, x0, y0, x1, y1):
         height = self.canvas.figure.bbox.height
-        y0 =  height-y0
-        y1 =  height-y1
-        try: self.lastrect
-        except AttributeError: pass
-        else: self.canvas._tkcanvas.delete(self.lastrect)
+        y0 = height - y0
+        y1 = height - y1
+        if hasattr(self, "lastrect"):
+            self.canvas._tkcanvas.delete(self.lastrect)
         self.lastrect = self.canvas._tkcanvas.create_rectangle(x0, y0, x1, y1)
 
         #self.canvas.draw()
@@ -751,7 +749,8 @@ def set_cursor(self, cursor):
         self.window.configure(cursor=cursord[cursor])
 
     def _Button(self, text, file, command, extension='.gif'):
-        img_file = os.path.join(rcParams['datapath'], 'images', file + extension)
+        img_file = os.path.join(
+            rcParams['datapath'], 'images', file + extension)
         im = Tk.PhotoImage(master=self, file=img_file)
         b = Tk.Button(
             master=self, text=text, padx=2, pady=2, image=im, command=command)
@@ -761,10 +760,11 @@ def _Button(self, text, file, command, extension='.gif'):
 
     def _Spacer(self):
         # Buttons are 30px high, so make this 26px tall with padding to center it
-        s = Tk.Frame(master=self, height=26, relief=Tk.RIDGE, pady=2, bg="DarkGray")
+        s = Tk.Frame(
+            master=self, height=26, relief=Tk.RIDGE, pady=2, bg="DarkGray")
         s.pack(side=Tk.LEFT, padx=5)
         return s
-        
+
     def _init_toolbar(self):
         xmin, xmax = self.canvas.figure.bbox.intervalx
         height, width = 50, xmax-xmin
@@ -776,11 +776,11 @@ def _init_toolbar(self):
 
         for text, tooltip_text, image_file, callback in self.toolitems:
             if text is None:
-                # Add a spacer -- we don't need to use the return value for anything
+                # Add a spacer; return value is unused.
                 self._Spacer()
             else:
                 button = self._Button(text=text, file=image_file,
-                                   command=getattr(self, callback))
+                                      command=getattr(self, callback))
                 if tooltip_text is not None:
                     ToolTip.createToolTip(button, tooltip_text)
 
@@ -789,7 +789,6 @@ def _init_toolbar(self):
         self._message_label.pack(side=Tk.RIGHT)
         self.pack(side=Tk.BOTTOM, fill=Tk.X)
 
-
     def configure_subplots(self):
         toolfig = Figure(figsize=(6,3))
         window = Tk.Tk()
@@ -846,17 +845,11 @@ def save_figure(self, *args):
 
     def set_active(self, ind):
         self._ind = ind
-        self._active = [ self._axes[i] for i in self._ind ]
+        self._active = [self._axes[i] for i in self._ind]
 
     def update(self):
         _focus = windowing.FocusManager()
         self._axes = self.canvas.figure.axes
-        naxes = len(self._axes)
-        #if not hasattr(self, "omenu"):
-        #    self.set_active(range(naxes))
-        #    self.omenu = AxisMenu(master=self, naxes=naxes)
-        #else:
-        #    self.omenu.adjust(naxes)
         NavigationToolbar2.update(self)
 
 
@@ -900,8 +893,7 @@ def showtip(self, text):
         except Tk.TclError:
             pass
         label = Tk.Label(tw, text=self.text, justify=Tk.LEFT,
-                      background="#ffffe0", relief=Tk.SOLID, borderwidth=1,
-                      )
+                         background="#ffffe0", relief=Tk.SOLID, borderwidth=1)
         label.pack(ipadx=1)
 
     def hidetip(self):
@@ -919,20 +911,13 @@ def draw_rubberband(self, x0, y0, x1, y1):
         height = self.figure.canvas.figure.bbox.height
         y0 = height - y0
         y1 = height - y1
-        try:
-            self.lastrect
-        except AttributeError:
-            pass
-        else:
+        if hasattr(self, "lastrect"):
             self.figure.canvas._tkcanvas.delete(self.lastrect)
-        self.lastrect = self.figure.canvas._tkcanvas.create_rectangle(x0, y0, x1, y1)
+        self.lastrect = self.figure.canvas._tkcanvas.create_rectangle(
+            x0, y0, x1, y1)
 
     def remove_rubberband(self):
-        try:
-            self.lastrect
-        except AttributeError:
-            pass
-        else:
+        if hasattr(self, "lastrect"):
             self.figure.canvas._tkcanvas.delete(self.lastrect)
             del self.lastrect
 
@@ -954,8 +939,8 @@ def __init__(self, toolmanager, window):
         self.pack(side=Tk.TOP, fill=Tk.X)
         self._groups = {}
 
-    def add_toolitem(self, name, group, position, image_file, description,
-                     toggle):
+    def add_toolitem(
+            self, name, group, position, image_file, description, toggle):
         frame = self._get_groupframe(group)
         button = self._Button(name, image_file, toggle, frame)
         if description is not None:
diff --git a/lib/matplotlib/colorbar.py b/lib/matplotlib/colorbar.py
index a080eb59247c..6e0d34830d87 100644
--- a/lib/matplotlib/colorbar.py
+++ b/lib/matplotlib/colorbar.py
@@ -1117,9 +1117,10 @@ def make_axes(parents, location=None, orientation=None, fraction=0.15,
     parent_anchor = kw.pop('panchor', loc_settings['panchor'])
     pad = kw.pop('pad', loc_settings['pad'])
 
-    # turn parents into a list if it is not already
-    if not isinstance(parents, (list, tuple)):
-        parents = [parents]
+    # turn parents into a list if it is not already. We do this w/ np
+    # because `plt.subplots` can return an ndarray and is natural to
+    # pass to `colorbar`.
+    parents = np.atleast_1d(parents).ravel()
 
     fig = parents[0].get_figure()
     if not all(fig is ax.get_figure() for ax in parents):
@@ -1164,24 +1165,36 @@ def make_axes(parents, location=None, orientation=None, fraction=0.15,
     return cax, kw
 
 
+# helper functions for row,col to index.
+def index2rowcolunm(index, ncols):
+    col = index%ncols + 1
+    row = int(np.floor(index/ncols)+1)
+    return row, col
+
+
+def rowcolunm2index(row, col, ncols):
+    index = col-1+(row-1)*ncols
+    return index
+
+
 @docstring.Substitution(make_axes_kw_doc)
-def make_axes_gridspec(parent, **kw):
+def make_axes_gridspec(parents, **kw):
     '''
-    Resize and reposition a parent axes, and return a child axes
+    Resize and reposition a list of parent axes, and return a child axes
     suitable for a colorbar. This function is similar to
-    make_axes. Prmary differences are
+    make_axes. Primary differences are
 
      * *make_axes_gridspec* only handles the *orientation* keyword
        and cannot handle the "location" keyword.
 
-     * *make_axes_gridspec* should only be used with a subplot parent.
+     * *make_axes_gridspec* should only be used with subplot parents.
 
      * *make_axes* creates an instance of Axes. *make_axes_gridspec*
         creates an instance of Subplot.
 
      * *make_axes* updates the position of the
-        parent. *make_axes_gridspec* replaces the grid_spec attribute
-        of the parent with a new one.
+        parents. *make_axes_gridspec* replaces the grid_spec attribute
+        of the parents with new ones.
 
     While this function is meant to be compatible with *make_axes*,
     there could be some minor differences.
@@ -1212,17 +1225,52 @@ def make_axes_gridspec(parent, **kw):
     pad_s = (1. - shrink) * 0.5
     wh_ratios = [pad_s, shrink, pad_s]
 
+    # make parents a 1-d ndarray if its not already...
+    parents = np.atleast_1d(parents).ravel()
+    # For the subplotspec that these axes belong to, loop through and get
+    # the maximum and minimum index into the subplotspec.  The result is the
+    # size the new gridspec that we will create must be.
+    gsp0 = parents[0].get_subplotspec().get_gridspec()
+    minind = 10000
+    maxind = -10000
+    for parent in parents:
+        gsp = parent.get_subplotspec().get_gridspec()
+        if gsp == gsp0:
+            ss = list(parent.get_subplotspec().get_geometry())
+            if ss[3] is None:
+                ss[3] = ss[2]
+            if ss[2] < minind:
+                minind = ss[2]
+            if ss[3] > maxind:
+                maxind = ss[3]
+        else:
+            raise NotImplementedError('List of axes passed to colorbar '
+             'must be from the same gridspec or call to plt.subplots')
+    # map the extent of the gridspec from indices to rows and columns.
+    # We need this below to assign the parents into the new gridspec.
+    ncols0 = gsp0.get_geometry()[1]
+    minrow, mincol = index2rowcolunm(minind, ncols0)
+    maxrow, maxcol = index2rowcolunm(maxind, ncols0)
+    nrows = maxrow-minrow+1
+    ncols = maxcol-mincol+1
+
+    # this is subplot spec the region that we need to resize and add
+    # a colorbar to.
+    subspec = gridspec.SubplotSpec(gsp0, minind, maxind)
+
     gs_from_subplotspec = gridspec.GridSpecFromSubplotSpec
     if orientation == 'vertical':
         pad = kw.pop('pad', 0.05)
         wh_space = 2 * pad / (1 - pad)
 
+        # split the subplotspec containing parents into two, with one only
+        # `fraction` wide for the colorbar, and the other with some padding.
         gs = gs_from_subplotspec(1, 2,
-                                 subplot_spec=parent.get_subplotspec(),
+                                 subplot_spec=subspec,
                                  wspace=wh_space,
                                  width_ratios=[x1 - pad, fraction]
                                  )
-
+        # center the colorbar vertically.
         gs2 = gs_from_subplotspec(3, 1,
                                   subplot_spec=gs[1],
                                   hspace=0.,
@@ -1236,7 +1284,7 @@ def make_axes_gridspec(parent, **kw):
         wh_space = 2 * pad / (1 - pad)
 
         gs = gs_from_subplotspec(2, 1,
-                                 subplot_spec=parent.get_subplotspec(),
+                                 subplot_spec=subspec,
                                  hspace=wh_space,
                                  height_ratios=[x1 - pad, fraction]
                                  )
@@ -1251,12 +1299,40 @@ def make_axes_gridspec(parent, **kw):
         anchor = (0.5, 1.0)
         panchor = (0.5, 0.0)
 
-    parent.set_subplotspec(gs[0])
-    parent.update_params()
-    parent.set_position(parent.figbox)
-    parent.set_anchor(panchor)
+    # we need to repackage the parent axes into gs.
+    # We need to know where they are in the new gs.
+    # the new gs has nrows by ncols.
+    gsnew = gs_from_subplotspec(nrows, ncols, subplot_spec=gs[0])
+
+    for parent in parents:
+        geo = parent.get_subplotspec().get_geometry()
+        ncol0 = geo[1]
+
+        # remap the old min gridspec index (geo[2]) into a new
+        # index.
+        oldrow, oldcol = index2rowcolunm(geo[2], ncol0)
+        newrow = oldrow - minrow+1
+        newcol = oldcol - mincol+1
+        newminind = rowcolunm2index(newrow, newcol, ncols)
+
+        # remap the old max gridspec index (geo[3]) into a new
+        # index.
+        if geo[3] is None:
+            newmaxind = newminind
+        else:
+            oldrow, oldcol = index2rowcolunm(geo[3], ncol0)
+            newrow = oldrow - minrow+1
+            newcol = oldcol - mincol+1
+            newmaxind = rowcolunm2index(newrow, newcol, ncols)
+
+        # change the subplotspec for this parent.
+        parent.set_subplotspec(
+            gridspec.SubplotSpec(gsnew, newminind, newmaxind))
+        parent.update_params()
+        parent.set_position(parent.figbox)
+        parent.set_anchor(panchor)
 
-    fig = parent.get_figure()
+    fig = parents[0].get_figure()
     cax = fig.add_subplot(gs2[1])
     cax.set_aspect(aspect, anchor=anchor, adjustable='box')
     return cax, kw
diff --git a/lib/matplotlib/contour.py b/lib/matplotlib/contour.py
index 82d9fb023312..5d3fc1126c0d 100644
--- a/lib/matplotlib/contour.py
+++ b/lib/matplotlib/contour.py
@@ -1254,11 +1254,11 @@ def _process_colors(self):
             i0, i1 = 0, len(self.levels)
             if self.filled:
                 i1 -= 1
-            # Out of range indices for over and under:
-            if self.extend in ('both', 'min'):
-                i0 = -1
-            if self.extend in ('both', 'max'):
-                i1 += 1
+                # Out of range indices for over and under:
+                if self.extend in ('both', 'min'):
+                    i0 -= 1
+                if self.extend in ('both', 'max'):
+                    i1 += 1
             self.cvalues = list(range(i0, i1))
             self.set_norm(colors.NoNorm())
         else:
diff --git a/lib/matplotlib/figure.py b/lib/matplotlib/figure.py
index 7034ea64c0d0..1cb952b3d322 100644
--- a/lib/matplotlib/figure.py
+++ b/lib/matplotlib/figure.py
@@ -1794,12 +1794,12 @@ def colorbar(self, mappable, cax=None, ax=None, use_gridspec=True, **kw):
         """
         if ax is None:
             ax = self.gca()
+        ax = np.atleast_1d(ax).ravel()
 
         # Store the value of gca so that we can set it back later on.
         current_ax = self.gca()
-
         if cax is None:
-            if use_gridspec and isinstance(ax, SubplotBase):
+            if use_gridspec and isinstance(ax[0], SubplotBase):
                 cax, kw = cbar.make_axes_gridspec(ax, **kw)
             else:
                 cax, kw = cbar.make_axes(ax, **kw)
diff --git a/lib/matplotlib/mlab.py b/lib/matplotlib/mlab.py
index ae9143c98f5a..971770790c40 100644
--- a/lib/matplotlib/mlab.py
+++ b/lib/matplotlib/mlab.py
@@ -727,12 +727,12 @@ def _spectral_helper(x, y=None, NFFT=None, Fs=None, detrend_func=None,
     elif mode == 'psd':
         result = np.conj(result) * result
     elif mode == 'magnitude':
-        result = np.abs(result)
+        result = np.abs(result) / np.abs(windowVals).sum()
     elif mode == 'angle' or mode == 'phase':
         # we unwrap the phase later to handle the onesided vs. twosided case
         result = np.angle(result)
     elif mode == 'complex':
-        pass
+        result /= np.abs(windowVals).sum()
 
     if mode == 'psd':
 
diff --git a/lib/matplotlib/patches.py b/lib/matplotlib/patches.py
index 10bc425b7734..36a9c8e30b93 100644
--- a/lib/matplotlib/patches.py
+++ b/lib/matplotlib/patches.py
@@ -3995,6 +3995,10 @@ def transmute(self, path, mutation_size, linewidth):
 class FancyArrowPatch(Patch):
     """
     A fancy arrow patch. It draws an arrow using the :class:`ArrowStyle`.
+
+    The head and tail positions are fixed at the specified start and end points
+    of the arrow, but the size and shape (in display coordinates) of the arrow
+    does not change when the axis is moved or zoomed.
     """
     _edge_default = True
 
diff --git a/lib/matplotlib/tests/baseline_images/test_axes/magnitude_spectrum_freqs_dB.png b/lib/matplotlib/tests/baseline_images/test_axes/magnitude_spectrum_freqs_dB.png
index ebc50c676692..15d32d399208 100644
Binary files a/lib/matplotlib/tests/baseline_images/test_axes/magnitude_spectrum_freqs_dB.png and b/lib/matplotlib/tests/baseline_images/test_axes/magnitude_spectrum_freqs_dB.png differ
diff --git a/lib/matplotlib/tests/baseline_images/test_axes/magnitude_spectrum_freqs_linear.png b/lib/matplotlib/tests/baseline_images/test_axes/magnitude_spectrum_freqs_linear.png
index 14f832a7355b..9dec3eef4339 100644
Binary files a/lib/matplotlib/tests/baseline_images/test_axes/magnitude_spectrum_freqs_linear.png and b/lib/matplotlib/tests/baseline_images/test_axes/magnitude_spectrum_freqs_linear.png differ
diff --git a/lib/matplotlib/tests/baseline_images/test_axes/magnitude_spectrum_noise_dB.png b/lib/matplotlib/tests/baseline_images/test_axes/magnitude_spectrum_noise_dB.png
index a18d0b40f43b..a8ceb982774b 100644
Binary files a/lib/matplotlib/tests/baseline_images/test_axes/magnitude_spectrum_noise_dB.png and b/lib/matplotlib/tests/baseline_images/test_axes/magnitude_spectrum_noise_dB.png differ
diff --git a/lib/matplotlib/tests/baseline_images/test_axes/magnitude_spectrum_noise_linear.png b/lib/matplotlib/tests/baseline_images/test_axes/magnitude_spectrum_noise_linear.png
index c2deb9e2414d..95a64798607b 100644
Binary files a/lib/matplotlib/tests/baseline_images/test_axes/magnitude_spectrum_noise_linear.png and b/lib/matplotlib/tests/baseline_images/test_axes/magnitude_spectrum_noise_linear.png differ
diff --git a/lib/matplotlib/tests/baseline_images/test_contour/contour_manual_colors_and_levels.png b/lib/matplotlib/tests/baseline_images/test_contour/contour_manual_colors_and_levels.png
index 6de9c579758d..c4ec5f0beed4 100644
Binary files a/lib/matplotlib/tests/baseline_images/test_contour/contour_manual_colors_and_levels.png and b/lib/matplotlib/tests/baseline_images/test_contour/contour_manual_colors_and_levels.png differ
diff --git a/lib/matplotlib/tests/test_backend_pdf.py b/lib/matplotlib/tests/test_backend_pdf.py
index 3529ea8541db..d52fc3efdf66 100644
--- a/lib/matplotlib/tests/test_backend_pdf.py
+++ b/lib/matplotlib/tests/test_backend_pdf.py
@@ -178,6 +178,8 @@ def test_grayscale_alpha():
     ax.set_yticks([])
 
 
+# This tests tends to hit a TeX cache lock on AppVeyor.
+@pytest.mark.flaky(reruns=3)
 @needs_tex
 def test_missing_psfont(monkeypatch):
     """An error is raised if a TeX font lacks a Type-1 equivalent"""
diff --git a/lib/matplotlib/tests/test_backend_ps.py b/lib/matplotlib/tests/test_backend_ps.py
index 8ead41d67d01..cd6e5feae14a 100644
--- a/lib/matplotlib/tests/test_backend_ps.py
+++ b/lib/matplotlib/tests/test_backend_ps.py
@@ -27,6 +27,8 @@
     reason="This test needs a TeX installation")
 
 
+# This tests tends to hit a TeX cache lock on AppVeyor.
+@pytest.mark.flaky(reruns=3)
 @pytest.mark.parametrize('format, use_log, rcParams', [
     ('ps', False, {}),
     needs_ghostscript(('ps', False, {'ps.usedistiller': 'ghostscript'})),
diff --git a/lib/matplotlib/tests/test_basic.py b/lib/matplotlib/tests/test_basic.py
index 236e0d9e7d8d..945e78322b3d 100644
--- a/lib/matplotlib/tests/test_basic.py
+++ b/lib/matplotlib/tests/test_basic.py
@@ -20,7 +20,8 @@ def test_override_builtins():
         '__spec__',
         'any',
         'all',
-        'sum'
+        'sum',
+        'divmod'
     }
 
     # We could use six.moves.builtins here, but that seems
diff --git a/lib/matplotlib/tests/test_contour.py b/lib/matplotlib/tests/test_contour.py
index 5e2211066f3c..eb2be0991ad6 100644
--- a/lib/matplotlib/tests/test_contour.py
+++ b/lib/matplotlib/tests/test_contour.py
@@ -168,21 +168,22 @@ def test_given_colors_levels_and_extends():
     levels = [2, 4, 8, 10]
 
     for i, ax in enumerate(axes.flatten()):
-        plt.sca(ax)
-
         filled = i % 2 == 0.
         extend = ['neither', 'min', 'max', 'both'][i // 2]
 
         if filled:
-            last_color = -1 if extend in ['min', 'max'] else None
-            plt.contourf(data, colors=colors[:last_color], levels=levels,
-                         extend=extend)
+            # If filled, we have 3 colors with no extension,
+            # 4 colors with one extension, and 5 colors with both extensions
+            first_color = 1 if extend in ['max', 'neither'] else None
+            last_color = -1 if extend in ['min', 'neither'] else None
+            c = ax.contourf(data, colors=colors[first_color:last_color],
+                            levels=levels, extend=extend)
         else:
-            last_level = -1 if extend == 'both' else None
-            plt.contour(data, colors=colors, levels=levels[:last_level],
-                        extend=extend)
+            # If not filled, we have 4 levels and 4 colors
+            c = ax.contour(data, colors=colors[:-1],
+                           levels=levels, extend=extend)
 
-        plt.colorbar()
+        plt.colorbar(c, ax=ax)
 
 
 @image_comparison(baseline_images=['contour_datetime_axis'],
diff --git a/lib/matplotlib/tests/test_mathtext.py b/lib/matplotlib/tests/test_mathtext.py
index f913445ac6c1..544d3ef89201 100644
--- a/lib/matplotlib/tests/test_mathtext.py
+++ b/lib/matplotlib/tests/test_mathtext.py
@@ -167,9 +167,6 @@ def baseline_images(request, fontset, index):
     return ['%s_%s_%02d' % (request.param, fontset, index)]
 
 
-# See #7911 for why these tests are flaky and #7107 for why they are not so
-# easy to fix.
-@pytest.mark.flaky(reruns=3)
 @pytest.mark.parametrize('index, test', enumerate(math_tests),
                          ids=[str(index) for index in range(len(math_tests))])
 @pytest.mark.parametrize('fontset',
@@ -184,9 +181,6 @@ def test_mathtext_rendering(baseline_images, fontset, index, test):
              horizontalalignment='center', verticalalignment='center')
 
 
-# See #7911 for why these tests are flaky and #7107 for why they are not so
-# easy to fix.
-@pytest.mark.flaky(reruns=3)
 @pytest.mark.parametrize('index, test', enumerate(font_tests),
                          ids=[str(index) for index in range(len(font_tests))])
 @pytest.mark.parametrize('fontset',
diff --git a/lib/matplotlib/tests/test_tightlayout.py b/lib/matplotlib/tests/test_tightlayout.py
index 76d9c1424212..03ac60a3e0d0 100644
--- a/lib/matplotlib/tests/test_tightlayout.py
+++ b/lib/matplotlib/tests/test_tightlayout.py
@@ -58,7 +58,7 @@ def test_tight_layout3():
 
 
 @image_comparison(baseline_images=['tight_layout4'],
-                  freetype_version=('2.4.5', '2.4.9'))
+                  freetype_version=('2.5.5', '2.6.1'))
 def test_tight_layout4():
     'Test tight_layout for subplot2grid'
 
diff --git a/lib/matplotlib/text.py b/lib/matplotlib/text.py
index b11ae28ba0cc..caa5dcdaf73f 100644
--- a/lib/matplotlib/text.py
+++ b/lib/matplotlib/text.py
@@ -907,11 +907,12 @@ def get_prop_tup(self, renderer=None):
         need to know if the text has changed.
         """
         x, y = self.get_unitless_position()
+        renderer = renderer or self._renderer
         return (x, y, self.get_text(), self._color,
                 self._verticalalignment, self._horizontalalignment,
                 hash(self._fontproperties),
                 self._rotation, self._rotation_mode,
-                self.figure.dpi, id(renderer or self._renderer),
+                self.figure.dpi, id(renderer), getattr(renderer, '_uid', 0),
                 self._linespacing
                 )
 
diff --git a/setup.cfg.template b/setup.cfg.template
index e8ba46861b60..3bb835d1def8 100644
--- a/setup.cfg.template
+++ b/setup.cfg.template
@@ -13,19 +13,19 @@
 # set this to True.  It will download and build a specific version of
 # FreeType, and then use that to build the ft2font extension.  This
 # ensures that test images are exactly reproducible.
-#local_freetype = False
+local_freetype = True
 
 [status]
 # To suppress display of the dependencies and their versions
 # at the top of the build log, uncomment the following line:
-#suppress = True 
+#suppress = True
 
 [packages]
 # There are a number of subpackages of Matplotlib that are considered
 # optional. All except tests are installed by default, but that can
 # be changed here.
 #
-#tests = False
+tests = True
 #sample_data = True
 #toolkits = True
 # Tests for the toolkits are only automatically installed
diff --git a/setupext.py b/setupext.py
index 1b2506da2c6b..15c59053c2b9 100644
--- a/setupext.py
+++ b/setupext.py
@@ -1341,7 +1341,7 @@ def add_flags(self, ext):
                                        default_libraries=['qhull'])
         else:
             ext.include_dirs.append('extern')
-            ext.sources.extend(glob.glob('extern/libqhull/*.c'))
+            ext.sources.extend(sorted(glob.glob('extern/libqhull/*.c')))
 
 
 class TTConv(SetupPackage):