問題描述：
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
已放棄 (核心已轉儲)
明明已經install libgtk2.0-dev and pkg-config 爲什麼還會報出上述錯誤，上述錯誤提醒和網上網友給出的解釋，可以認爲，在安裝opencv之前必須先安裝libgtk2.0-dev and pkg-config，後安裝他們兩個或者忘記安裝都會報出上述錯誤。
可是筆者已經將opencv完整卸載並且重新cmake編譯安裝過之後，依然會報出上述問題，重新安裝，重啓系統，安裝不同版本等都試過了，還是報錯，怎麼破。筆者就在這上面折騰了一整天，終於解決了。。
解決辦法如下：
a. 首先完整卸載opencv，並且刪除與opencv有關的全部文件，完整刪除opencv的方法參見【Ubuntu-Opencv】Ubuntu14.04 Opencv3.3.0 完整卸載方案；
b. 然後要記得把libgtk2.0-dev先卸載，卸載方案如下：
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* (我是用的前面的安裝）
pkg-config –modversion gtk+-2.0 安裝好可以用這個命令查看gtk+-2.0安裝版本
c. 最後重新cmake安裝opencv，安裝方法參考【Ubuntu-Opencv】Ubuntu14.04 Opencv3.3.0 安裝配置及測試
按照上述abc，我已經完美解決上述問題