@@ -4096,6 +4096,11 @@ def pick(self, *args):
         martist.Artist.pick(self, args[0])
 
     def get_default_bbox_extra_artists(self):
+        """
+        Return a default list of artists that are used for the bounding box
+        calculation.  Artists are excluded either by not being visible
+        or ``artist.inbbox = False``.
+        """
         return [artist for artist in self.get_children()
                 if (artist.get_visible() and artist.inbbox)]
 
@@ -4105,8 +4110,8 @@ def get_tightbbox(self, renderer, call_axes_locator=True,
         Return the tight bounding box of the axes, including axis and their
         decorators (xlabel, title, etc).
 
-        Artists that have ``artist.inbbox=False`` are not included
-        in the bbox.  
+        Artists that have ``artist.inbbox = False`` are not included
+        in the bbox.
 
         Parameters
         ----------
 
@@ -2002,6 +2002,9 @@ def get_tightbbox(self, renderer, bbox_extra_artists=None):
         """
         Return a (tight) bounding box of the figure in inches.
 
+        Artists that have ``artist.inbbox = False`` are not included
+        in the bbox.
+
         Parameters
         ----------
         renderer : `.RendererBase` instance
@@ -2084,6 +2087,10 @@ def tight_layout(self, renderer=None, pad=1.08, h_pad=None, w_pad=None,
         """
         Automatically adjust subplot parameters to give specified padding.
 
+        To exclude an artist on the axes from the bounding box calculation
+        that determines the subplot parameters (i.e. legend, or annotation),
+        then set `a.inbbox=False` for that artist.
+
         Parameters
         ----------
         pad : float
 
@@ -172,7 +172,7 @@ def example_plot(ax, fontsize=12, nodec=False):
 
 fig, ax = plt.subplots(constrained_layout=True)
 ax.plot(np.arange(10), label='This is a plot')
-ax.legend(loc='center left', bbox_to_anchor=(0.9, 0.5))
+ax.legend(loc='center left', bbox_to_anchor=(0.8, 0.5))
 
 #############################################
 # However, this will steal space from a subplot layout:
@@ -181,7 +181,39 @@ def example_plot(ax, fontsize=12, nodec=False):
 for ax in axs.flatten()[:-1]:
     ax.plot(np.arange(10))
 axs[1, 1].plot(np.arange(10), label='This is a plot')
-axs[1, 1].legend(loc='center left', bbox_to_anchor=(0.9, 0.5))
+axs[1, 1].legend(loc='center left', bbox_to_anchor=(0.8, 0.5))
+
+#############################################
+# In order for a legend or other artist to *not* steal space
+# from the subplot layout, it can have its ``inbbox`` property
+# set to ``False``.  Of course this can mean the legend ends up
+# cropped, but can be useful if the plot is subsequently called
+# with ``fig.savefig('outname.png', bbox_inches='tight')``.  Note,
+# however, that the legend's inbbox status will have to be
+# toggled again to make the saved file work:
+
+fig, axs = plt.subplots(2, 2, constrained_layout=True)
+for ax in axs.flatten()[:-1]:
+    ax.plot(np.arange(10))
+axs[1, 1].plot(np.arange(10), label='This is a plot')
+leg = axs[1, 1].legend(loc='center left', bbox_to_anchor=(0.8, 0.5))
+leg.inbbox = False
+wanttoprint = False
+if wanttoprint:
+    leg.inbbox = True
+    fig.do_constrained_layout(False)
+    fig.savefig('outname.png', bbox_inches='tight')
+
+#############################################
+# A better way to get around this awkwardness is to simply
+# use a legend for the figure:
+fig, axs = plt.subplots(2, 2, constrained_layout=True)
+for ax in axs.flatten()[:-1]:
+    ax.plot(np.arange(10))
+lines = axs[1, 1].plot(np.arange(10), label='This is a plot')
+labels = [l.get_label() for l in lines]
+leg = fig.legend(lines, labels, loc='center left',
+                 bbox_to_anchor=(0.8, 0.5), bbox_transform=axs[1, 1].transAxes)
 
 ###############################################################################
 # Padding and Spacing
 
@@ -10,6 +10,10 @@
 feature and may not work for some cases. It only checks the extents
 of ticklabels, axis labels, and titles.
 
+See also constrained_layout for a different way to do the same things as
+tight-layout:
+:doc:`/tutorials/intermediate/constrainedlayout_guide`
+
 
 Simple Example
 ==============
@@ -280,6 +284,35 @@ def example_plot(ax, fontsize=12):
                             None, 1 - (gs2.top-top)],
                  h_pad=0.5)
 
+###############################################################################
+# Legends and Annotations
+# =======================
+#
+# Pre Matplotlih 2.2, legends and annotations were excluded from the bounding
+# box calculations that decide the layout.  Subsequently these artists were
+# added to the calculation, but sometimes it is undesirable to include them.
+# For instance in this case it might be good to have the axes shring a bit
+# to make room for the legend:
+
+fig, ax = plt.subplots(figsize=(4, 3))
+lines = ax.plot(range(10), label='A simple plot')
+ax.legend(bbox_to_anchor=(0.7, 0.5), loc='center left',)
+fig.tight_layout()
+plt.show()
+
+###############################################################################
+# However, sometimes this is not desired (quite often when using
+# ``fig.savefig('outname.png', bbox_inches='tight')``).  In order to
+# remove the legend from the bounding box calculation, we simply set its
+# bounding ``inbbox=False`` and the legend will be ignored.
+
+fig, ax = plt.subplots(figsize=(4, 3))
+lines = ax.plot(range(10), label='B simple plot')
+leg = ax.legend(bbox_to_anchor=(0.7, 0.5), loc='center left',)
+leg.inbbox = False
+fig.tight_layout()
+plt.show()
+
 ###############################################################################
 # Use with AxesGrid1
 # ==================