title: Unable to build open cv 2.3.1 source code
body: <p>I installed open cv in my ubuntu 11.04. But whenever I try to run any code I get the following error:</p>
  
  <p>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 /home/robik/Downloads/Java/OpenCV-2.3.1/modules/highgui/src/window.cpp, line 275
  terminate called after throwing an instance of 'cv::Exception'
    what():  /home/robik/Downloads/Java/OpenCV-2.3.1/modules/highgui/src/window.cpp:275: 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</p>
  
  <p>I already have libgtk2.0-dev and pkg-config in my OS. What should I do?</p>