问题描述：
ubuntu@ubuntu:~/opencv-3.3.0/cpp_luckynote/opencv_lena$ ./DisplayImage ../lfw/Anna_Chicherova/Anna_Chicherova_0001.jpg
OpenCV Error: Unspecified error (The function is not implemented. Rebuild the library with Windows, GTK+ 2.x or Carbon support. If you are on Ubuntu or Debian, install libgtk2.0-dev and pkg-config, then re-run cmake or configure script) in cvNamedWindow, file /opt/conda/conda-bld/opencv_1491943414359/work/opencv-3.1.0/modules/highgui/src/window.cpp, line 527
terminate called after throwing an instance of 'cv::Exception'
what(): /opt/conda/conda-bld/opencv_1491943414359/work/opencv-3.1.0/modules/highgui/src/window.cpp:527: error: (-2) The function is not implemented. Rebuild the library with Windows, GTK+ 2.x or Carbon support. If you are on Ubuntu or Debian, install libgtk2.0-dev and pkg-config, then re-run cmake or configure script in function cvNamedWindow
已放弃 (核心已转储)
明明已经install libgtk2.0-dev and pkg-config 为什么还会报出上述错误，上述错误提醒和网上网友给出的解释，可以认为，在安装opencv之前必须先安装libgtk2.0-dev and pkg-config，后安装他们两个或者忘记安装都会报出上述错误。
可是笔者已经将opencv完整卸载并且重新cmake编译安装过之后，依然会报出上述问题，重新安装，重启系统，安装不同版本等都试过了，还是报错，怎么破。笔者就在这上面折腾了一整天，终于解决了。。
解决办法如下：
a. 首先完整卸载opencv，并且删除与opencv有关的全部文件，完整删除opencv的方法参见【Ubuntu-Opencv】Ubuntu14.04 Opencv3.3.0 完整卸载方案；
b. 然后要记得把libgtk2.0-dev先卸载，卸载方案如下：
sudo apt-get autoremove gtk+-2.0
sudo apt-get install gnome-core-devel
sudo apt-get install libgtk2.0-dev 或者 sudo apt-get install libgtk2.0* (我是用的前面的安装）
pkg-config –modversion gtk+-2.0 安装好可以用这个命令查看gtk+-2.0安装版本
c. 最后重新cmake安装opencv，安装方法参考【Ubuntu-Opencv】Ubuntu14.04 Opencv3.3.0 安装配置及测试
按照上述abc，我已经完美解决上述问题