title: How to include wxWidgets headers in CMake project
body: <p>I am trying to run wxWidget example using cmake but unable to include the headers of wxWidgets in my C++ project(CMakeLists.txt). If i run the program using the command</p>
  <pre><code>g++ main.cpp `wx-config --cppflags --libs` -o wxTest
  </code></pre>
  <p>the program works and display the window. But how can i do that using CMakeLists.txt file. For example, usually i create a separate folder called external-libs and then inside it create a folder with the name <em>whateverlibraryname</em> and then inside it create a header and src and lib folder where i place the header files, any source files and .so files respectively. But in the case of wxWidgets i have several static library files and also inside the header there are many separate folders and i don't know how to include them all. They produce the error:</p>
  <pre><code>fatal error: wx/wx.h: No such file or directory
   #include &lt;wx/wx.h&gt;
  </code></pre>
  <p>I am using Ubuntu 18.04 and my project directory structure is as follows:</p>
  <pre><code>├── build
  └── source
      ├── CMakeLists.txt
      ├── external-libraries
      │   └── wxWidgets
      │       ├── headers
      │       │   ├── msvc
      │       │   │   └── wx
      │       │   └── wx
      │       │       ├── android
      │       │       ├── aui
      │       │       ├── dfb
      │       │       ├── generic
      │       │       ├── gtk
      │       │       ├── gtk1
      │       │       ├── html
      │       │       ├── meta
      │       │       ├── motif
      │       │       ├── msw
      │       │       ├── osx
      │       │       ├── persist
      │       │       ├── private
      │       │       ├── propgrid
      │       │       ├── protocol
      │       │       ├── qt
      │       │       ├── ribbon
      │       │       ├── richtext
      │       │       ├── stc
      │       │       ├── univ
      │       │       ├── unix
      │       │       ├── x11
      │       │       ├── xml
      │       │       └── xrc
      │       ├── lib   
                  ├── libwx_baseu-3.1.a
      │       │   ├── libwx_baseu_net-3.1.a
      │       │   ├── libwx_baseu_xml-3.1.a
      │       │   ├── libwx_gtk3u_adv-3.1.a
      │       │   ├── libwx_gtk3u_aui-3.1.a
      │       │   ├── libwx_gtk3u_core-3.1.a
      │       │   ├── libwx_gtk3u_gl-3.1.a
      │       │   ├── libwx_gtk3u_html-3.1.a
      │       │   ├── libwx_gtk3u_propgrid-3.1.a
      │       │   ├── libwx_gtk3u_qa-3.1.a
      │       │   ├── libwx_gtk3u_ribbon-3.1.a
      │       │   ├── libwx_gtk3u_richtext-3.1.a
      │       │   ├── libwx_gtk3u_stc-3.1.a
      │       │   ├── libwx_gtk3u_xrc-3.1.a
      │       │   ├── libwxjpeg-3.1.a
      │       │   ├── libwxregexu-3.1.a
      │       │   ├── libwxscintilla-3.1.a
      │       │   └── libwxtiff-3.1.a
      │       └── src
      ├── main.cpp
      
  </code></pre>
  <p><strong>Main.cpp</strong> has <code>#include&lt;wx/wx.h&gt;</code> at the top. I am using VSCode and when i ran the program using g++(command described above) it works but doesn't workwhen i run the same program using CMake. That is how to include the header folder and use the lib folder that contains all the wxWidgets headers and library files. What should be the contents of the CMakeLists.txt files and what are the other necessary things that i have to do to make this work.</p>