title: Matplotlib change style of inset elements singularly
body: <p>I am trying to plot some data on which I would like to make an inset to show some details.
  It is quite easy to create the inset and set the characteristics of the plot inside the inset.</p>
  
  <p>What I have found cumbersome is how to set the properties of the inset itself, in particular the color and thickness of the inset frame, of the small box indicating where the plot is sampled and the lines to connect the small box to the inset.
  What I would need is to change them singularly. I know it is possible to change the properties of the mark_inset as a single piece, but not as separated parts.</p>
  
  <p>Let's say, as example, the inset frame should be thinner and dashed, the sampling box thicker and red and the connecting lines dotted and of the same color as in the MWE.</p>
  
  <p>Here is the MWE:</p>
  
  <pre><code>import scipy as sc
  import matplotlib.pyplot as plt
  from cycler import cycler
  from mpl_toolkits.axes_grid1.inset_locator import inset_axes
  from mpl_toolkits.axes_grid1.inset_locator import mark_inset
  plt.close('all')
  
  color = plt.get_cmap('viridis')(sc.linspace(0, 1, 4)[1:3])
  params_IEEEtran = {'legend.fontsize': 10,
                     'axes.labelsize': 10,
                     'axes.titlesize': 10,
                     'xtick.labelsize': 9,
                     'ytick.labelsize': 9,
                     'mathtext.fontset': 'stix',
                     'font.family': 'Times New Roman',
                     'mathtext.rm': 'serif',
                     'mathtext.bf': 'serif:bold',
                     'mathtext.it': 'serif:italic',
                     'mathtext.sf': 'sans\\-serif',
                     'grid.color': 'k',
                     'grid.linestyle': ':',
                     'grid.linewidth': 0.5,
                     'axes.xmargin': 0,
                     'axes.axisbelow': False,
                     'lines.linewidth': 1.0,
                     'legend.frameon': False,
                     'axes.prop_cycle': cycler('color', plt.get_cmap('viridis')(
                             sc.linspace(0, 1, 4))),
                     'figure.figsize': [3, 2.4],
                     }
  plt.rcParams.update(params_IEEEtran)
  
  x = sc.linspace(0.1, 100)
  y1 = sc.array(sc.sqrt(x)).T
  y2 = sc.array(1/sc.sqrt(x)).T
  
  fig = plt.figure('FIG')
  ax = fig.add_subplot(1, 1, 1)
  ax.plot(x, y1)
  
  ax_twinx = ax.twinx()
  ax_twinx.plot(x, y2)
  
  ax.set_xlim(0, 100)
  ax.set_ylim(0, 10)
  ax_twinx.set_ylim(0, 1)
  
  inset = fig.add_axes([0.6, 0.3, 0.12, 0.35], frameon=False)
  inset.axes.get_xaxis().set_visible(False)
  inset.axes.get_yaxis().set_visible(False)
  
  inset.plot(x, y1)
  
  inset_twinx = inset.twinx()
  inset_twinx.axes.get_yaxis().set_visible(False)
  
  inset_twinx.plot(x, y2)
  
  inset.set_xlim(5, 15)
  inset.set_ylim(2, 4)
  inset_twinx.set_ylim(0.2, 0.4)
  
  mark_inset(ax, inset, loc1=4, loc2=2, lw=0.3,
             fc="none", ec=color[0], zorder=200)
  fig.savefig('./example.png', bbox_inches='tight', dpi=300)
  </code></pre>
  
  <p>And here result:</p>
  
  <p><a href="https://i.stack.imgur.com/vcea9.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/vcea9.png" alt="enter image description here"></a></p>