Gtk-ERROR : GTK+ 2.x symbols detected. Using GTK+2.x and GTK+3 in the same process is not support
Gtk-ERROR **: GTK+ 2.x symbols detected. Using GTK+ 2.x and GTK+3 in the same process is not support
程序员遇到这种环境问题的时候前列腺都不好， 记录一下， 方便以后回查～
报错：
报错有两种形式
形式1：
Gtk-ERROR **: GTK+ 2.x symbols detected. Using GTK+ 2.x and GTK+3 in the same process is not support
形式2：
Gtk-Message: 18:20:57.303: Failed to load module "canberra-gtk-module"
原因
一般原因：
python 里 matplotlib 的 gtk使用版本（TK3AGG）与系统后端默认（一般是TKAGG）的gtk版本不一样，有时候就算你没用上import matplotlib包，opencv或者别的什么包也用到了, 一样报错， 其直接结果就是imshow没有图片。
本人原因：
我的情况是我写的rospy节点里面用到了opencv-python， ros节点在后面运行的时候， 其它用c++写的节点在使用cv::imshow()的时候运行报错程序而且程序还不崩只是没有图片。
报错的一般复现
下面脚本可以简单检查自己是否有这种版本冲突的问题：
import cv2
import matplotlib.plot as plt
cv2.namedWindow("test")
解决方案
这里我使用这个方案， 因为别的像 重新编译opencv， 太头大了：
命令行输入：
quit()
会显示一个文件：
/etc/matplotlibrc
接着命令行输入，
sudo gedit /etc/matplotlibrc
会出现这么个文件
### MATPLOTLIBRC FORMAT
# This is a sample matplotlib configuration file - you can find a copy
# of it on your system in
# site-packages/matplotlib/mpl-data/matplotlibrc. If you edit it
# there, please note that it will be overwritten in your next install.
# If you want to keep a permanent local copy that will not be
# overwritten, place it in the following location:
# unix/linux:
# $HOME/.config/matplotlib/matplotlibrc or
# $XDG_CONFIG_HOME/matplotlib/matplotlibrc (if $XDG_CONFIG_HOME is set)
# other platforms:
# $HOME/.matplotlib/matplotlibrc
#
# See http://matplotlib.org/users/customizing.html#the-matplotlibrc-file for
# more details on the paths which are checked for the configuration file.
#
# This file is best viewed in a editor which supports python mode
# syntax highlighting. Blank lines, or lines starting with a comment
# symbol, are ignored, as are trailing comments. Other lines must
# have the format
# key : val # optional comment
#
# Colors: for the color values below, you can either use - a
# matplotlib color string, such as r, k, or b - an rgb tuple, such as
# (1.0, 0.5, 0.0) - a hex string, such as ff00ff - a scalar
# grayscale intensity such as 0.75 - a legal html color name, e.g., red,
# blue, darkslategrayGTKAgg GTKCairo GTK3Agg GTK3Cairo
# MacOSX Qt4Agg Qt5Agg TkAgg WX WXAgg Agg Cairo GDK PS PDF SVG
#### CONFIGURATION BEGINS HERE
# The default backend; one of GTK GTKAgg GTKCairo GTK3Agg GTK3Cairo
# MacOSX Qt4Agg Qt5Agg TkAgg WX WXAgg Agg Cairo GDK PS PDF SVG
# Template.
# You can also deploy your own backend outside of matplotlib by
# referring to the module name (which must be in the PYTHONPATH) as
# 'module://my_backend'.
#
# If you omit this parameter, it will always default to "Agg", which is a
# non-interactive backend.
backend : GTKAgg
# If you are using the Qt4Agg backend, you can choose here
# to use the PyQt4 bindings or the newer PySide bindings to
# the underlying Qt4 toolkit.
#backend.qt4 : PyQt4 # PyQt4 | PySide
# Note that this can be overridden by the environment variable
# QT_API used by Enthought Tool Suite (ETS); valid values are
# "pyqt" and "pyside". The "pyqt" setting has the side effect of
# forcing the use of Version 2 API for QString and QVariant.
# The port to use for the web server in the WebAgg backend.
# webagg.port : 8888
把 GTKAgg改成GTKAgg GTKCairo GTK3Agg GTK3Cairo MacOSX Qt4Agg Qt5Agg TkAgg WX WXAgg Agg Cairo GDK PS PDF SVG中的一个， 这个GTKAgg应该是gtk+2.0, 可以改成GTK3Agg, 由于在jetson板子上问题的原因可能多种多样这里建议使用QT5Agg。因为python2 pip 好像已经不支持QT4了， 所以还没安装的话只能下载QT5。
x86架构下
pip install PyQt5
Arm架构下（jetson）
sudo apt-get install qt5-doc qt5-doc-html qtbase5-doc-html qtbase5-examples -y
保存以后问题的复现就没有了。
另外多提一句：
如果是在x86架构下（就是我们正常的电脑）其实可以降opencv-python的版本
pip install opencv-python==3.4.0
或许可行， 但是我仔细想想可能不够稳。
另外：
千万别神经刀删除GTK 比如 sudo apt-get purge gtk2.0-dev && sudo apt-get autoremove 那你的环境基本凉了， 因为你见到的很多基础的视觉库都是基于GTK这个基础的可视化包依赖来开发的，系统会删除使用GTK为依赖的所有库。
参考文献
非常非常感谢这几个链接
https://github.com/opencv/opencv/issues/6680
https://github.com/yosinski/deep-visualization-toolbox/issues/10
https://www.cnblogs.com/longwhite/p/10397754.html
正是同行的分享才可以让很多问题变得方便。
祝， 武运昌隆～