Cannot remove thumbnails on Plots pane

Description

I cannot remove thumnails of plots pane when using lastest master.

What steps will reproduce the problem?

1. Plot to figure browser

2. delete figure or delete thumnail

Versions

• Spyder version: 4.0.0.dev0 d84908e66
• Python version: 3.7.3
• Qt version: 5.9.6
• PyQt5 version: 5.9.2
• Operating System: Linux 5.3.6-1-MANJARO

Dependencies

cloudpickle >=0.5.0          :  1.2.1 (OK)
pygments >=2.0               :  2.4.2 (OK)
qtconsole >=4.5.5            :  4.5.5 (OK)
nbconvert >=4.0              :  5.5.0 (OK)
sphinx >=0.6.6               :  2.1.2 (OK)
pylint >=0.25                :  2.3.1 (OK)
psutil >=0.3                 :  5.6.3 (OK)
qtawesome >=0.5.7            :  0.5.7 (OK)
qtpy >=1.5.0                 :  1.8.0 (OK)
pickleshare >=0.4            :  0.7.5 (OK)
zmq >=17                     :  18.0.0 (OK)
chardet >=2.0.0              :  3.0.4 (OK)
numpydoc >=0.6.0             :  0.9.1 (OK)
spyder_kernels >=1.5.0;<2.0.0:  1.6.0 (OK)
qdarkstyle >=2.7             :  2.7 (OK)
atomicwrites >=1.2.0         :  1.3.0 (OK)
diff_match_patch >=20181111  :  20181111 (OK)
watchdog                     :  None (OK)
keyring                      :  None (OK)
pexpect >=4.4.0              :  4.7.0 (OK)
pympler                      :  None (OK)
sympy >=0.7.3                :  1.4 (OK)
cython >=0.21                :  0.29.12 (OK)
IPython >=4.0                :  7.6.1 (OK)
matplotlib >=2.0.0           :  3.1.0 (OK)
pandas >=0.13.1              :  0.24.2 (OK)
numpy >=1.7                  :  1.16.4 (OK)
scipy >=0.17.0               :  1.3.0 (OK)
pyls >=0.28.2;<0.29.0        :  0.28.3 (OK)
xdg >=0.26                   :  0.26 (OK)
rtree >=0.8.3                :  0.8.3 (OK)

[steff456]

I can reproduce this on Linux and on Mac! I will work in this one 😃

[ccordoba12]

I can’t reproduce this on Linux.