[Bug]: Contour plot is not updating after customization made to the color bar in the generated plot.

[JishnuJeevan]

Bug summary

A contour plot is plotted with the minimum and maximum values of the parameter as color bar limits. Then when I try to make changes (such as limits and colormap) to the color bar from the toolbar of the generated plot it is not updating accordingly.

1. A sample plot.
   
2. Customizing the color bar.
   
3. Options for changing the color bar.
   
4. The changes are reflected in the color bar, but not in the plot.
   Kindly suggest how I can update the plot according to the changes made in the color bar options.

Code for reproduction

# A sample code.
import numpy as np
import matplotlib.pyplot as plt

origin = 'lower'

delta = 0.025

x = y = np.arange(-3.0, 3.01, delta)
X, Y = np.meshgrid(x, y)
Z1 = np.exp(-X**2 - Y**2)
Z2 = np.exp(-(X - 1)**2 - (Y - 1)**2)
Z = (Z1 - Z2) * 2

nr, nc = Z.shape

# put NaNs in one corner:
Z[-nr // 6:, -nc // 6:] = np.nan
# contourf will convert these to masked


Z = np.ma.array(Z)
# mask another corner:
Z[:nr // 6, :nc // 6] = np.ma.masked

# mask a circle in the middle:
interior = np.sqrt(X**2 + Y**2) < 0.5
Z[interior] = np.ma.masked

fig1, ax2 = plt.subplots(constrained_layout=True)
CS = ax2.contourf(X, Y, Z, 10, cmap=plt.cm.bone, origin=origin)

# Note that in the following, we explicitly pass in a subset of the contour
# levels used for the filled contours.  Alternatively, we could pass in
# additional levels to provide extra resolution, or leave out the *levels*
# keyword argument to use all of the original levels.

CS2 = ax2.contour(CS, levels=CS.levels[::2], colors='r', origin=origin)

ax2.set_title('Nonsense (3 masked regions)')
ax2.set_xlabel('word length anomaly')
ax2.set_ylabel('sentence length anomaly')

# Make a colorbar for the ContourSet returned by the contourf call.
cbar = fig1.colorbar(CS)
cbar.ax.set_ylabel('verbosity coefficient')
# Add the contour line levels to the colorbar
cbar.add_lines(CS2)
plt.show()

Actual outcome

Expected outcome

The following changes have been made to the code in order to get the expected plot.
lev = np.linspace(-0.5, 0.5, 10)
CS = ax2.contourf(X, Y, Z, 10, cmap=plt.cm.rainbow, origin=origin, levels=lev)

Additional information

No response

Operating system

Windows

Matplotlib Version

3.4.3

Matplotlib Backend

Qt5Agg

Python version

Python 3.8.12

Jupyter version

No response

Installation

pip

[anntzer]

Closed by #25247: the contour plot now appears as a normal entry in the "images, etc." tab of the main axes.
Whether direct manipulation of the contour plot cmap (or ylims, for that matter) should work is another question, but right now it doesn't and it seems reasonable to say that it shouldn't.