Bug report

Bug summary

Using plt.clabel(manual=True) adds labels but the labels are not easily readable because only a small gap is created in the contour.

Code for reproduction

The following works:

plt.figure()
x = np.arange(400).reshape((20,20))
c = plt.contour(x)
plt.clabel(c)

But the following doesn't give as nice a result:

plt.figure()
x = np.arange(400).reshape((20,20))
c = plt.contour(x)
plt.clabel(c, manual=True)
# click around

This happens with both the Qt5 and MacOS X backends, and I am using a retina display.

Matplotlib version

• Operating System: MacOS X 10.11
• Matplotlib Version: 2.0.2
• Python Version: 3.6.1